Kuro

He is a junior high school student who is [Ramune](https://anilist.co/character/187923)'s disciple and works as an assistant. He has good judgment and motor skills, as well as a rational mind. It's hard to understand his mood due to having a poker face and is always having to play the straight man when Ramune says or does anything. Kuro trusts Ramune's skills as a specialist of mystery diseases completely.