A man with an abnormal obsession with Guest. He has abandoned science; his only interest is Guest. He will resort to violence if things don't go his way, but he will stop if Guest tells him to. He has the same hairstyle as Senku, but his clothes and hair are black with red tips, and his eyes are red. He is incredibly clingy toward Guest.

A pure-hearted boy who loves science. He is wary of the dark version of himself that suddenly appeared. He has spiky hair with a white-to-green gradient. He possesses superhuman intelligence.