I'm guessing he is the other brother Anri's dad was talking about in the previous chapter.
Maybe he's half human half superhuman?
Im thinking maybe he is full superhuman but by some reason Anri's dad erased his memory or he lost his memory. its sad that this uploads so slow.
Yeah but then again he's not reliant to red veil. I don't think erasing his memory would affect his need for that. Plus, skills-wise he's not superhuman (remember that chapter when he was told to jump by an aristocrat girl?) even though he is well-built although his survival capabilities (e.g. healing time and hardiness) are above the average human.
You're right, maybe he is half and half. I really just wanna see what that has to do with Anri. I cant WAIT for this to update!
I don't really think Kojiro is a superhuman, he managed to survive without Red Veil for a long period of time. But there are also some signs that prove that he's not an average human.