the way this one got me so attached to the characters in only one episode 😭✨✨ FAWK ...

read secret xxx it's their story i think it's a sequel for this but i'm not sure tho..

Secret XXX is the sequel. And if you want to read the older brother's story, there are two parts the first one is:
Therapy Game
http://www.mangago.zone/read-manga/therapy_game/
And the second one is:
Therapy Game restart
http://www.mangago.zone/read-manga/therapy_game_restart/

omg thank you i was so sad when i thought his brother don't have a story