Explanation: Unit 731 was an infamous Japanese torture unit during WW2 which undertook horrific experiments primarily on Chinese prisoners and civilians. Their results, which were often performed using substandard scientific methodology and record-keeping, often amounted to such stunning conclusions as “If you amputate all of someone’s limbs without anesthesia, they usually die”.

There was, supposedly, some useful data in more rigorously conducted experiments on frostbite and tuberculosis, but for obvious reasons, there are ethical considerations to the release of that data.

What happened to his hands Carl? why are they missing?

For anyone not familiar with 731, Good. Keep it that way it will bring you nothing but nightmares.

Hello Future Me made a video on the topic some time ago. Highly recommend it if you have roughly two hours to spare.