Kuroi is incredibly interested in Mashiro, whom he serves like a goddess. Kuroi is cold-blooded, a psycho, and a yandere. He vows his life to protect Mashiro. Kuroi revealed himself that he also interested in humans in Chapter 2 when he caught a female enemy soldier tortured her for interrogation.

Spoiler

In chapter 7 it is also revealed that Kuroi is pretty popular among girls e.g. Kurumi and Moegi and it's revealed by Kuroi himself in the story that since a young age he's been able to read all situations and every single thought which lead to him being able to manipulate and hypnotize people perfectly. This chapter also revealed that Kuroi has used his power to gamble and have sex with random people in order to get money.

Spoiler

In chapter 8, the story revealed why Kuroi is so incredibly interested in Mashiro, in fact it is due to her being the only one that Kuroi can't read the thought of. The story also revealed that Kuroi forged documents, falsified school records and other stuff in order to protect Mashiro.