Military Swords of Imperial Japan

The whole aspect of the Kōa-Issin sword

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 South Manchuria Railway Co,Ltd (SMR). Dalian Railway Factory Sword Works
 published the explanatory of the swords "Kōa Issin" on July 25, 1939.
 SMR says an abbreviated name as "Mantetsu".
 The character of "Kōa Issin" of the cover of this explanatory was written by
 Yōsuke Matsuoka (next Foreign Minister) who was Mantetsu's President.
 The actual condition of the sword which Mantetsu manufactured became clear with
 this time. Usually, the actual condition of this blade currently called the
 "Mantetsu-tō " will surely sweep away the common saying of a world.
 By the discovered data, I will ask what a Japanese sword is.
 I describe the main point of this explanatory below.
 I want the concept of the Mantetsu-tō which the former mistook to be corrected.

← A special express "Asia number" and Mantetsu SMR's badge of a company.

 Mantetsu (head office: Dalian) is not a mere railway company. Japan won the Russo-Japanese War.
 Therefore, Japan yielded and received the railway rights and interests of Manchuria in the victory from Czarist Russia.
 Mantetsu is the national policy concern founded in 1906. Mantetsu developed various enterprises, such as ore industry, a coal mine shaft, iron manufacture, education, agriculture, city construction, medical treatment, and public works.
 Behind, Manchuria Heavy Industry Development Co,Ltd.(Mangyō = national policy concern) was founded, and many of Mantetsu's enterprises were transferred to Mangyo. Mantetsu was reduced to three sections, such as a railway, the Fushun coal mine shaft, and investigation. However, it was the mega industry which Mantetsu had the capital of the half scale of a national budget of Japan, the total extension of a railway had 10,000km, and the number of employees had 400,000 people (golden age), and reigned over Manchuria. Mantetsu's essence will not be able to be understood if the contents of this company are judged by a company name. If Mantetsu work "Kōa Issin" is read, it is clear that the Kōa-Issin swords are not a sword made with the easy way of thinking only for compensating the non-productivity of a Japanese sword.
 Mantetsu concentrated technical power and analyzed thoroughly the Japanese sword which depends on handmade from ancient
times. And they have held the strong point and the fault of steel materials and a sword making.
 They succeeded in the creation of a Japanese sword excellent in scientific power.
 I want to introduce the main point of the "Kōa-Issin sword" and to express my view.

The origin of the "Kōa-Issin sword"

 Japan had imported malleable iron from Sweden or other countries. Mantetsu was burdened with the mission which supports itself in this malleable iron. Dr. Kazuharu Kusaka of Mantetsu Central Experiment Station studied manufacture of malleable iron, and he succeeded in this development. He returned this at a comparatively low temperature by having used the rich iron ore from Manchuria as materials, and made good sponge iron. It succeeded in he using this sponge iron as materials further, and obtaining very excellent steel materials by a peculiar electric steelmaking method.
 Then, Mantetsu made one Japanese sword as an experiment in Dalian Railway Factory using these steel materials.
 This sword was splendid like the Ko-tō. The specialist appraised this sword as Tadayoshi of Hizen accidentally. Depending on this result, Mantetsu greatly acquired confidence. Then, Dalian Railway Factory planned Guntō manufacture for the first time in September, 1937.  President Matsuoka who got to know this paid his attention to the loftiness of the mystical soul which a Japanese sword has more from ancient times. He judged that a Japanese sword symbolized the undaunted Japanese spirit. He thought that it restricted to this Japanese sword above all, in order to have given 150,000 employees the true Mantetsu soul.
 As another background, the Japanese sword was very lacking for the China incident.
 The Guntō was further lacking although the manufacturer of a Japanese sword did his best in manufacture of a Japanese sword with might and main with expansion of Guntō demand. The excellent Guntō was still more lacking.
 In such a situation, Mantetsu received the request so that its best may be done in manufacture of a Japanese sword in
cooperation with a military from the Kantō gun(army) in December, 1937.
 President Matsuoka judged such a situation synthetically and he ordered manufacture of a Japanese sword passionately.

Naming of the "Kōa-Issin sword"

 Those days, Japan had hung up five tribes' (Japan, Korea, Manchuria, China, and Mongolian) harmony over the slogan.
 President Matsuoka put that wish and he named this sword the "Kōa-Issin tō" on March 23, 1939.
 With "Kōa Issin", it means that the race of Asia will unify the heart and will revive both Asia.
 The dream which Japan pictured to itself was entrusted to this sword.
 At this time, Mantetsu's Sword Factory was manufacturing 400 monthly outputs. These swords were supplied to the Italy envoy, an Army Chief of Staff, the Tianjin military, the Shanghai army and navy, and the Lushun Kaikōsha.
 The order of a sword poured in from every direction, and Mantetsu was busy with production.
Writer impressions:
 That Mantetsu challenged malleable iron manufacture is not the narrow purpose of making a Mantetsu sword and a railway product. Japan without resources asked Manchuria for the way of self-support. Execution of the national policy was left to Mantetsu. It is clear also from the mission with which Mantetsu was burdened that Mantetsu is not a mere railay company. Development of malleable iron was the part. Those days, many elite engineers had gathered to the Mantetsu and coal industry which are important star industry.
 It seems that the engineer was naturally conscious of the "Sweden steel" and the "Tamahagane" which were said for
purity to be high. Sweden steel was used for the saber blade or the Murata sword in the Ttōkytō Artillery Arsenal, and the Tamahagane was used for the Japanese sword. Probably, it will be natural to have thought of the Japanese sword to the verification from Manchuria "malleable iron" which engineers developed themselves.
 At this time, they are considered that there was nothing in mind, such as mass production of a Japanese sword.
 The trial production of a Japanese sword guesses that verification of "malleable iron" was the purpose.
 However, the Japanese sword made as an experiment was a splendid sword like a "Ko-tō".
 In the trial cut(Tameshi-giri), this sword cut well and was strong to the break and the bend.
 There is no concrete publication of the sword making of this Japanese sword made as an experiment.

 President Matsuoka got to know the fact, the demand from the Kantō Gun(army) also
overlapped, and, probably, the truth opted for production of a Guntō.

 The founder of a Mantetsu sword was Mr. Kodo Suzuki the first head of the Mantetsu
Sword Factory.
 He devised the new sword making called a "new Japanese sword".

                     President Mantetsu SMR Yōsuke Matsuoka →

The structure and the forging method of a blade

 A Mantetsu sword uses the "Kusaka malleable iron" which Dr. Kusaka developed. The feature of Mr. Kodo Suzuki's sword making is having devised the carbon steel pipe containing the suitable carbon for skin steel. The sword inserted the core steel of low carbon into this carbon steel pipe, and was made from the machine forge welding. A blade is a perfect laminate constraction. Mantetsu called this sword making the "Moro-zutsumi" Type forging method peculiar to a railway factory.
 The greatest feature of the "Moro-zutsumi" Type is that the core steel is regularly contained in the inside of a blade.
 As for the blade of a laminate constraction, in a Japanese sword from ancient times, it is rare that the core steel is regularly contained. If a handmade blade from ancient times is cut and the section is seen, the core steel is irregularly contained as shown in the following figures.

 @ As for the blade of a handmade laminate constraction 
   from ancient times, a core steel becomes very irregular.
 Writer notes: Not all Japanese swords are laminate-constraction
 structures. It is the structure with a possibility that a blade may
  break with adoption of a hard Tamahagane devised mainly after the

 A The Moro-zutsumi sword making of a Mantetsu blade
    can arrange a core steel ideally

 Like the upper photograph, five places of the blade of a Kōa-Issin sword were cut.
 It is clear that any portion's core steel is regularly contained in the central part in the form of an ideal.
 In addition, it can be checked how the skin steel and the core steel have joined completely with the microphotograph
of a blade section. (A microscope enlargement is omitted)

Writer impressions:
If the organization microphotograph of arrangement junction of a core steel and a skin steel is seen, it can check that the junction part has united splendidly.
 It has been said until now that it is possible since the repetition forge welding of a double fold is "Japanese steel", and "Western steel" cannot carry out a forge welding easily.
 The forge welding from Manchuria "Western steel" extracted from the steel stone was splendidly possible.
 As long as this fact is seen, the common saying of a sword community does not have any basis.

 Next, for research, 2-3 blades of a Japanese sword from ancient times were cut, and a picture of the organization of the arrangement junction to a core steel and a skin steel was taken in the photograph.

Section of the blade


← Kōa-Issin sword

 SMR inserted and forged soft steel to pipe-like hard steel.
 Unlike the forge of a hand, distribution of hard steel and soft steel is ideal.

 Black is hard steel. and white is soft steel.

 SMR called this "the Moro package forging." 

Japanese sword from ancient times.

← This is a "Shizu Saburō Kaneuji"(Ko-tō) forged blade.

 Black is hard steel. and white is soft steel.

 As a result of mixing hard steel and soft steel, it became like the one-piece forging.
 This may be the fourth generation Kaneuji of a Shin-tō.

Japanese sword from ancient times.

← This is the "Sagaminokami Fujiwara Hiroshige"(Shin-tō) forged blade.

 Black is hard steel. and white is soft steel.

 Arrangement of a skin steel and a core steel has collapsed completely.
 Was it the intention of Shihōzume ? A skin steel is mixed also in a core steel.
 It cannot be called a laminate constraction any longer.

Writer impressions:
 Therefore, a handmade Japanese sword from ancient times was made by experience and intuition of a swordsmith Originally, the laminate constraction was a simple sword making.
 In spite of it, it was the consistent sword making that an extraordinary swordsmith imposed serious time and effort, and could be realized barely.
 It seems that it is mixed when weld a core and the skin steel together.
 Therefore, 80-90% of the blade of a laminate constraction had imperfect distribution of steel.
 On such the actual condition, reservation of arms performance is difficult.
 These photographs prove the fall with the actually made sword to the intention of a swordsmith.
 The Mantetsu sword has realized the laminate constraction of an ideal to a handmade Japanese sword.


 In order that the tempering method from ancient times might make heating temperature an average, the swordsmith suffered troubles very much.
 The hardening of a Kōa-Issin sword used the peculiar heating furnace. Heating temperature was very average and the temperature of the fixed purpose was obtained with the calorimeter.
 It was indispensable to the stability of the quality of a sword that it could always temper at a stable temperature.
 The hardness of an edge is the most important element that influences the sharpness(Kireaji) of a Japanese sword.
 Hardening temperature influences the hardness of an edge directly. A hard edge carries out an edge gap(Hagire) and a nicked edge(Hakobore).
 If a temper is insufficient, it will bend at a sword. This balance is the most difficult.
 Then, hardness determined as reference the hardness of the Japanese sword which depends on research of Dr. Tawara of Tōkyō Imperial University.

Share hardness table
The Mei of a sword
The surface of an edge
The reverse side of an edge
Maximum Minimum
 Muramasa(Second) 72 50 57 70 50 57 57
 Hiromitsu(Truth) 75  60 66 77 59 58 67
 Suishinshi Masahide(Truth) 74 52 68 81 60 68 68
 Kanesada(Truth) 71 50 63 68 45 61 62
70 45 61 66 50 60 60
 Koa Issin 72  50 57 71 50 57 57

Writer impressions:
 The hardness table of the typical Japanese sword which D.Eng.
Tawara of Tōkyō Imperial University packed is hung up, and the hardness of a Kōa-Issin sword is measured.
 It seems that it was based on "Muramasa of the second generation" since the Kōa-Issin sword was completely in agreement
with many data of "Muramasa".
 This hardness shows that a Kōa-Issin sword is a pliant blade like a Ko-tō.
 The quality of a sword is determined in the instant of a hardening.
 Conventionally, it depended for the hardening of a sword on a long experience and the intuition of a swordsmith.
 The swordsmith thought the law of Providence uncontrollable by its ability at the time of a hardening.
 The hardening was surely performed with the prayer of a swordsmith.
 Mantetsu conquered this difficult hardening by the power of modernistic science.
 They realized satisfactory blade hardness to the heating furnace which controls temperature freely.
 This was the epoch-making change of a Japanese sword manufacture process same with the idea of a carbon steel pipe skin
 The figure and size of a blade were determined by instruction of a military.
 The Kōa-Issin sword did not break, did not bend, but it cut well, and, moreover, was aimed at cheap abundant production.
 If the chemical component of a Kōa-Issin sword and the chemical component of the various Japanese swords by Dr. Tawara's research are shown, it will be as in the next table. (The chemical component table of 29 kinds of typical Japanese swords was omitted)

The chemical component of a Kōa-Issin sword

 Skin steel 0.57 0.05 0.17 0.018 0.003
 Core steel  0.23 0.15
0.21 0.020 0.008

In this chemical component, a sulphuric content is 0.004% or less so that clearly. The Kōa-Issin sword shows the same ingredient as the Japanese sword in the chemical component table of Dr. Tawara research.
 This was successful by progress of modern science. Unless excellent original steel is used a long time ago, in order to reduce the amount of carbon, and sulfur content this much, the swordsmith suffered troubles very much.
 Therefore, the swordsmith had to carry out the forge of the steel no less than 10 times and no less than 15 times.
 It will be not containing titanium if the Kōa-Issin sword feature is shown further. From ancient times, the iron sand of a Japanese inland contained a lot of titanium.
 This had the bad influence on sword material very much.
 The old swordsmith repeated serious efforts, in order to remove this.
 In happiness and the ore from Manchuria, this titanium does not contain at all.
 That is, the biggest features of a Kōa-Issin sword are not containing this titanium and 0.004% or less in sulfur.

Raw material

 Mantetsu investigated 12 ingredients, such as iron ore of Manchuria (six places) and North China (two places), and Japanese eight places) iron sand.
 The ratio of malleable iron (only the place of production exceeding 60% is extracted from the text) and titanium

Iron ore and an iron sand ingredient table

Rate of malleable iron
Titanium oxide
 Manchuria  Mukden Gyushindai 72.00% nothing
 Mukden Kyuchourei 69.06% nothing
 North China  Shandong Kinryokan 61.51% nothing
 Japan  Shimane Uemura 61.85% 4.42%
 Hiroshima Koyakkamura 60.42% 5.79%

Writer impressions:
 The rate of malleable iron of the iron ore from Manchuria has two overwhelmingly high places.
 Although there were three places of production where a malleable iron ratio is bad, there was all no titanium content except for one very small quantity.
 There is very much each titanium content of the iron sand of Japanese every place.
 A malleable iron ratio has low Aomori (45.09%) and Iwate (51.78%).
 As long as this ingredient table is seen, the Tamahaganes made from iron sand are not good steel materials.
 Rather, the Manchuria iron ore excels Japanese iron sand in the rate of malleable iron, and titanium content very much.

An examination and a result

1. Trial cut:
 The green bamboo with a diameter of 1.5cm was put in into volume straw with a diameter of 21.2cm, and it was cut perpendicularly and aslant.
 It was cut splendidly. The edge gap and the nicked edge did not carry out.
2. Living thing cut:
 The head of a pig with a weight of 97.5kg and a length around a head of 85cm was cut splendidly. The edge gap and the nicked edge did not carry out.
3. Mineuchi examination:
 The upper part of a stick with a width of 18cm and a length of 30.3cm was made into the cone, and grain was made into lengthwise.
 Mine of a sword was continuously struck 2 or 3 times to the head of this stick.
 Although 3mm curvature occurred in the blade, the edge gap and the nicked edge did not carry out.
4. Griddle cut:
 The soft steel board with the thickness of 0.15cm, a width of 3cm, and a length of 180cm was cut to four sheets in piles.
 The edge gap and the nicked edge did not carry out.
5. Standing tree cut of withered bamboo and acacia:
 The bamboo with a diameter of 6cm which withered, and an acacia with a diameter of 6cm are cut.
 The edge gap and the nicked edge did not carry out.
6. Low temperature test:
 One room of a Railway Research Institute Dalian Part Place was borrowed, and indoor temperature was set as 40 below the freezing point degrees C.
 The blade was left in this room 1 night.
 This blade is taken out on the next day, and it examines by striking the side of a blade against an iron constant board soon. The edge gap and the nicked edge did not carry out.
   Writer notes:
   Description of blade performance which has withstood cold appears only here.
   The Japanese sword from ancient times became weak like glass in the cold district.
   The Kwantung Army which has jurisdiction Manchuria is considered to have required the performance which withstands
   with chill of the Mantetsu sword naturally.
   The blade performance which withstands with this chill is the big feature of a Kōa-Issin sword.
   However, it is guessed that this was described briefly because of military secrecy.
7. Examination which cuts paper:
 The magazine king (620 pages per volume) who piled up two volumes was cut comfortably.
 The abbreviation half has cut the third magazine. The edge gap and the nicked edge did not have all.

Writer synthesis view

 A handmade Japanese sword has the remarkably bad efficiency of a sword making.
 Most labors of a swordsmith are spent on making material (Tamahagane) for a sword.
 The traditional forging is the work of making steel materials.
 Mantetsu prepared the oxygen of a proper quantity chemically beforehand to the developed malleable iron, and remove the process which forges steel materials.
 Moreover, in order to realize an ideal laminate constraction, the method of inserting and carrying out the forge welding of the soft iron into a carbon steel pipe skin steel was devised.
 Mantetsu realized very simply blade structure where an extraordinary swordsmith might be successful barely.
 Mantetsu had caught the essence of a Japanese sword correctly.
 Therefore, Mantetsu was able to carve the purpose and manufacture means of a sword clearly.
 They did the maximum use of the power of modern science at this manufacture means.
 If the hardness table of a blade is seen, the hardness of a Koa-Issin sword understands the same thing as a Ko-tō.
 Mr. Kanji Naruse who fixed the Guntō in the China battle line has said, "A Mantetsu sword is pliant like a Ko-tō".
 It was proved from this data that his words were right.
 By scientific power, the hardness of a Shin-tō or a Shin-Shin-tō was also reproducible.
 However, they dared have chosen the hardness of a Ko-tō.
 Mantetsu knew that the Ko-to was most excellent as a Japanese sword.
 And they mass-produced the blade of the performance which exceeds an ordinary Japanese sword in the stable quality.
 Here was the essence of a "Kōa-Issin sword".
 The Kōa-Issin sword is equipped also with the Masame-jihada(grain) and the Hamon of the blade.
 The Kōa-Issin sword was the grand trial which Mantetsu risked prestige and tackled in order to cultivate the world of
a new Japanese sword.
 This explanatory is the data which Mantetsu distributed to the persons concerned.
 Therefore, description of the concrete manufacturing process of a Kōa-Issin sword and a production facility is not indicated from a trade secret.
 It can be said that this is unavoidable.
 However, it can be understood about what kind of sword the Kōa-Issin sword was.

 The sword which Mantetsu made is classifiable into the following three sorts.
 @ The blade before being named "Kōa Issin". This blade has only Mantetsu's trademark stamp in a Tang.
 A A blade with "Kōa-Issin" Mei named the Kōa-Issin sword .
 B A blade with the stamp of the "Nan" of a Nanman Arsenal, and the stamp of "Ren" of a Nanman Arsenal Dalian factory.      There is no Mei of "Kōa Issin" in this blade. The blade made in Nanman Arsenal from the middle of 1943 is seemed.
 The difference in these three sorts of blades is not known.

The picture of a Mantetsu sword and a Tang is here

                     Since November 27, 2013 無料カウンター 
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