Yes I thought the same!! but then red hair (forgot his name too hahaha we're a lost cause! is it Ginu?) knows that Yumin (B??) is gay since he saw how black hair masturbates... So he knows that Yumin does not see the girl this way...
The black hair is really nice to show the red hair how him masturbate. I thought his just jerk but he was playing his ass.. (⊙…⊙ )..
Well, my best friends (she's a girl) boyfriend also masturbates in that way (why do I even know this... Sometimes I question my choice in friends XD) and he's totally straight, so red hair maybe isn't totally sure black hair must be gay? (Or he can just think black hair is bisexual too :p)
Ohhhhh yes true! I didn't see it like that!! (づ￣ ³￣)づ
I think red hair want to stealing anyone that close with the black hair because he did not know who the black hair's likes. but it will make the black hair hurt the feeling because of the red hair's action. Sorry for bad english.. btw, i dont know the name because I always forget the name. Hahah