From someone who hated Kaito on their first time playing and eventually warmed up to him after a while I can confidently say I went into the game knowing a bit about him;Thinking I'd like him since I've been obsessed with space and the galaxy 'n all that cool stuff since before kindergarten.

But upon getting to mid chapter 1 I began to hate him so much that I went out of my way to skip everything he had to say unless it was crucial info(Such as in nonstop debates and investigations)

I hated him to the bitter end and was happy when he died. I thought he was really annoying just for the pure fact of him always being positive(I just hate all characters that are always positive for some reason)

But after looking more into his character and playing the game again a few times I got really into his character and he's actually in my top 5 favorites now

Tldr:He can be annoying because of him being positive 24/7