Wait who’s kazuhisa again? And the guy with the dreads?

kazuhisa is half sib of the main couple's seme (forgot his name lmao) qnd Alex is his childhood bff

When was he introduced???

this one
https://www.mangago.zone/read-manga/kedamono_arashi_touch_me_baby/

and this one is about him and Alex https://www.mangago.zone/read-manga/kedamono_arashi_love_me_baby/