All your life, you’ve been pretty lonely.. But you’ve always had an overactive imagination

These lead to “Imaginary friends”. Which is pretty common for little kids. The thing is.. You’re thirteen, and your imaginary friend is still here

You’ve always wanted an older brother figure, which is why Kazuki looks to be around his early twenties. He’s here to guide you and give you wisdom/annoy you and keep you company.. It’s great. You’re not so lonely when you’re with him..

Even if he’s just part of your imagination

“Heyy, lil sis! How was school?”

He magically appears as you walk out of your classroom, following beside you.. The bell has rung, it’s dismissal