Ok, the premise of the work is already clear, the protagonist is one of those shy ones who is bullied and has no confidence in herself and behold(it's kinda sad the bully seems to follow her everywhere she goes), the male protagonist will be her support point, making her have the willpower to act on things at the same time that she falls in love with him, I've seen hundreds of works like this so one more doesn't hurt to see lol, the character design is well drawn.
kai kinda reminds me of ash from banana fish(his visual)
it's because he said he could be her father and she seems underage but it's just the way the anime put the things, just the vibe. and these theme is common in animes so.. kinda ok i guess