In a previous paper on the subject of Unit 731, I argued that Japan, before and throughout the Pacific War (1931-1945), attempted to systemically bolster its imperial credentials as a colonizer by developing its scientific establishment, in an attempt to display that it had surpassed Western nations. The experiments conducted at Unit 731 contributed to this goal. Japanese medical professionals used Unit 731 as an opportunity to conduct experiments on humans, which social stigma and global scientific ethical standards had previously prevented. The results of the Unit’s experiments were disseminated worldwide in order to prove Japan’s capacity to contribute to global scientific establishments. Additionally, a broad range of sex experiments were also conducted using (mostly) female and child prisoners. When reviewing primary source material that relates to sexual experiments conducted at the facility, it seems that though the scientific or rational motivations underpinned some experiments, other sex crimes cannot be justified as anything other than gross excesses of senseless violence. While non sexual experiments could be justified as attempts to solve disease, display Japanese modernity, or collected research for the development of advanced biological weaponry, the obscenity of some sex acts committed cannot be justified by these motivations. Why were sex experiments unique? Why were women, whose limbs were black with disease, raped by multiple guards at once? Why were prisoners abused and defiled, as their children, who were the result of forced impregnation, watched? In terms of the abuses that occurred at Unit 731, it is easy to homogenize ‘sex experiments’ and ‘sex crimes’ as the same thing. However, when analyzing these grotesque incidents, it becomes clear that the guards of the facility were motivated by different factors during experiments, which I will contrast with sexual violence propagated against the inmate population. The distinction I will argue in this paper is that it was the guards, staff, and independent medical practitioners who perpetuated crimes against humanity (expressed in sexual form). In regard to this violent, they acted as individuals, independent from the military-scientific establishment that operated and conceived of the Unit and the clinical sex experiments.