>>2715140I think it's just random, I could say rem and Chino are both Minase inori, then chino and Aoba are both manga time serializations, but shinobu doesn't really have any connectiong. Just a fan book of girls they like i guess.
Calls them oretaku characters, but I haven't heard that used before in japanese so not sure can't see anythiung like that on pixiv either.
