YMMV / GU-L

• Complete Monster: Kouzou Osada is the leader of the mansion and the head of the ongoing government-funded "GU-L" project. Basing his experiments on the real-life research on Unit 731, Osada guides stray wanderers to rent out his mansion to experiment on them and creating the Ultimate Lifeform that is virtually unkillable, morphing countless victims into monstrous and violent experiments, and is not above using his own co-workers to further his research. Presumably coercing a maid into giving him children named Takaya and Takashi, Osada forcibly experiments on both for the same reasons, even reviving Takashi from his stillborn death from his experiments. Noticing Azumi was planning to betray him to save Takashi, Osada Brainwashed her with a parasite to follow his every command, such as poisoning the young Tsutomu. With his most recent experiment being subjecting young students into a Deadly Game to see if his experiments were deadly enough, Osada ultimately fuses with his own son's remains to create the so called "GU-L" to kill them, and even when he's defeated, he proclaims that he's unkillable and immortal.