Dr. Hisakichi Tokuda: Ambition, Experimentation, and War Crimes in Wartime Japan

by Sapphire Dingler

In the records of the Yokohama Class B/C War Crimes Trials, some figures emerge not as clear-cut villains, but as troubling studies in the complexity of ambition, science, and moral collapse. One such figure is Dr. Hisakichi Tokuda, a Japanese physician whose wartime experiments on prisoners of war led to his prosecution during the Yokohama Class B and C War Crimes Trials.
Born in Honjo-mura, Futomo in the Isa District of Kagoshima Prefecture, Tokuda was 31 years old at the time of his arraignment. He was married and had a large family, with three sisters and two brothers. Tokuda pursued his medical education at Keijo Medical College (in present-day Seoul, South Korea under Japanese occupation), completing a four-year program that would lead him to become a physician. He rose to the military rank of Captain, and his service would eventually station him at Shinagawa Hospital, where he gained infamy among the POWs. 

What sets Tokuda apart from many of his peers is the contradiction between his intellect and his actions. According to fellow medical personnel and witnesses, Tokuda was an intelligent, well-read physician, “head and shoulders above” his contemporaries. He maintained an extensive medical library, kept up with current medical literature, and had a particular interest in diseases of the chest. However, it was this intense curiosity, and perhaps a desire for personal glory, that led him down a dark path of unauthorized and dangerous human experimentation. This paired with the soy bean milk injections made Tokuda a feared man within Shinagawa Hospital POW camp. 

Tokuda thought that he could cure all paralysis through inducing fever “With that in mind he gave me a shot of hard lumpy sulphur mixed with castor oil, using a hypodermic needle that is designed for giving a spinal anesthesia --- I got one shot. The results were rough and our doctors managed to talk him out of giving us any more ---. It gave me a fever which lasted about four or five days. The first night, it drove me out of my head and I do not remember much of the second night either. It stiffened our legs so that we couldn't bend them. I could not feel it as I had paralysis. The other fellows who had beri-beri paralysis said it was quite painful. I recieved about twenty to thirty spinal injections of vitamin B-1 and C. They had no effect except psychologically as a lot of the men started walking to get away from the shots.” (Ex 8).

Williamson testified that he first came in contact with the drug, caprylic acid, in June 1945. He knew it as caprylicon, a white powder which they got from the Nishin Oil Company. A solution was made by dissolving it in distilled water. The accused selected six of the fattest, strongest, “TB” patients who were given intravenous injections of the solution three times a week. There were no reactions except for perspiration and “it assisted in losing weight” (R91). The accused also had Williamson give injections of caprylic acid mixed with bile (after centrifuging and boiling) to three TB patients (R92). Three paralysis patients in ward No. 5 were given injections of castor oil and sulphur by the accused in early July 1945. Each injection was given on the inside of the thigh. The effects were high fever, a burning pain from the waist down and vomiting. One man was still suffering from the effects when they were liberated. “The other two, I think, around about a fortnight, they still complained, but I didn’t put any strength in the other two complaints, but I did in the other man. The accused also gave intraspinal injections to some of the patients in ward No. 5. They had three injections.

“Then this Japanese Dr. Tokuda decided to inject intravenously a substance called ‘carbolic acid’ into many positive pulmonary TB cases, many of them with cavities, and following the injection, many of the patients felt an intense constriction in the chest as well as developing chills and fever. The only factor that stopped this brutal and inhuman form of treatment was that the B-29’s bombed out the factory producing this caprylic acid -- and the Japanese doctor was unable to obtain any more of this chemical.” (Ex 10). 
Between 1943 and 1945, Dr. Tokuda conducted a variety of experimental treatments on Allied prisoners of war. These included intravenous and intraspinal injections of caprylic acid, a compound related chemically to treatments used for leprosy, which Tokuda believed might have an effect on TB. The procedures were administered without consent and often without sound medical reasoning.
One such experiment involved injecting six strong TB patients with a distilled solution of caprylic acid three times a week. Others received injections mixed with bile or colloidal substances prepared by a chemist friend of Tokuda. The results were disturbing: while some patients experienced minor reactions like sweating and pain, others showed no clinical improvement, and X-rays even indicated worsening conditions. In some instances, he used unsterilized preparations, resulting in acute illness and severe pain among patients.

“Dr. Kescher, the pathologist, stated (EX 4) that Tokuda never told him why they used caprylic acid injections. His own hypothesis is that the TB organism is like the organism that causes leprosy in that it is an acid-fast organism. Caprylic acid is somewhat allied chemically to the active effect in leprosy, and Tokuda felt that the TB organism would be favorably affected by caprylic acid. The witness further stated that “These injections were given in various ways. Caprylic Acid was, in one group, injected full strength intravenously. In another group, caprylic acid with saline was injected. In another group, caprylic acid was injected in colloidal form. This colloid was made for Dr. Tokuda by one of his friends, a Japanese chemist. When this colloid form was no longer available, Dr. Tokuda sought a suitable medium for a colloid, and in several cases, used bile, which Keschner drain from patients. Sometimes we would use caprylic acid and glucose. Another mixture we used caprylic acid, desiccated American Red Cross blood plasma and ether. The patients who recieved these injections had various degrees of reactions such as coughing, pains in the chest, kidneys and mild fever. Clinically, there was no subjective improvement in the patients’ disease. X-ray films in several cases revealed some enlargement of the previous existing cavities. It is unfair from the medical point of view for me to state whether these cavities would have increased in size in the natural course of the disease or may have been aggravated in size by the caprylic acid treatment that these patients recieved. I doubt strongly whether these injections had any detrimental effects in the course of these diseases and the individuals. Other standard forms of accepted therapy for TB were carried out under Dr. Tokuda’s direction or by myself. It is noteworthy to mention that Dr. Tokuda was particularly interested in chest diseases and very intensive laboratory studies were carried out by him in studying the progress of this disease.

Dr. Tokuda also treated some of the beri-beri cases with thiamine-chloride intraspinal, and while his technique was not always painless and evoked considerable criticism from the patients, they all showed remarkable recovery after these treatments. On one occasion, Dr. Tokuda subjected several beri-beri patients to intra-spinal Riboflavin injections. The preparation we used was not adequately sterilized due to our lack of proper facilities and these patients were acutely ill for several days after these injections. Tokuda discontinued these injections when he saw these side reactions.” (p18 of 34, Tokuda, #186)

Patients suffering from Beri-beri, who recieved some injections intramuscularly (sic) of sulphur and castor oil from Dr. Tokuda. These patients, except for experiencing severe pains and discomfort for several days after the injections, were not harmed. 
His experimentation extended beyond TB. In a particularly brutal regimen, paralyzed and beri-beri patients received intramuscular injections of sulphur and castor oil, causing high fevers, vomiting, and severe pain. Some patients described being unable to bend their legs afterward, while others experienced fever so intense it left them delirious. Intraspinal injections of thiamine (Vitamin B1), riboflavin, nicotinic acid, acetylcholine, and even American Red Cross plasma mixed with ether were also administered—with little regard to dosage, sterility, or ethical boundaries. These procedures caused neurological complications, including meningitis-like symptoms in multiple prisoners.
Witnesses like Dr. Dawson-Grove and Dr. Kescher described Tokuda’s work as a blend of scientific curiosity and clinical recklessness. While some colleagues believed he genuinely hoped to discover new treatments, others—such as Dr. Gottlieb—condemned him as an inexperienced doctor engaging in “the most vicious type of experimentation.” Gottlieb accused Tokuda of striking patients for failing to salute him and using his medical authority to inflict suffering under the guise of treatment.
Henry Roy Hudson, a former prisoner, stated that in the later part of September 1943, he was beaten by Captain Tokuda because he asked for morphine for one of the patients (Ex 15).  (pg 19 of 34, Tokuda, Case #186)

Dr. Gottlied stated: “The Jap medical commandant, Dr. Tokuda, on numerous occasions struck patients because they were not quick enough to salute him. --- The Jap medical commandant, a young inexperienced doctor, took it upon himself to engage in the most vicious type of experimentation not based on any medical logic or previous experience and causing many of our patients innumerable instances of physical suffering--. In the first place he instituted a regime of giving intraspinal injections of vitamin B in large doses and when he started his experiments, he used nicotinic acid. -- He also gave “acetycholine” intraspinal -- a most dangerous drug, also vitamin C and Riboflavin, pure cruel experimentation. About twenty-five men were in this experimental group and at least 75 per cent of them developed terrific headaches, vomiting, stiffness of the neck, fever, and then some of them were tapped. Subsequently -- cloudy spinal fluid was obtained signifying the presence of meningitis. Many of the men also experiences severe excruciating pain along the spinal nerve.”
The experiments ceased only when the factory producing caprylic acid was bombed by American B-29s, cutting off Tokuda’s supply. His actions left a legacy of trauma and pain among the survivors. Prisoners reported lifelong complications from the injections, while others never fully recovered from the physical and psychological toll of his experiments.
Tokuda’s case, Docket Number 186, was initially sentenced to death by hanging, but later it was commuted to life in prison. It is unknown if he was one of the many paroled in 1958. Dr. Tokuda's actions were a breach of both medical ethics and international humanitarian law.





Bibliography

1. Stanford University Libraries, Virtual Tribunals. “Reviews of Yokohama Class B and Class C War Crimes Trials: Case Docket Number 186, Hisakichi Tokuda.” Accessed June 5, 2025. https://exhibits.stanford.edu/virtual-tribunals/catalog/mg979yc6070.
   
   
   
2. Japan Center for Asian Historical Records (JACAR). “Military Civil Information Documents.” B17070047400. https://www.jacar.archives.go.jp/acv/contents/pub/pdf/B17/B17070047400.BAdash_0002.RAdash-0036.0006.pdf
   
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