Because my raws' pages are random, so I didn't know yet but seems like so.
Kaji said he loved a guy in the past to Ritsuka, and the guy he meant is the one with him. Maybe they are an item? Because they live together. The black haired guy is a pro in violin. Kaji and the black haired guy always playing violin whenever they are together, like it's 'their time' only.
In vol 2, kaji asked the black haired guy to come to his mini concert. At first he was rejected, but the black haired guy surprised Kaji by coming to mini concert for real. The bkack haired guy still kind of wanting to know what kind of song Kaji's band will perform, until Mafuyu sings (it pains me seriously.... the scene and Mafuyu's feelings are so damn asdfghjkl). The black haired surprised with it and stay longer by smoking another one.
Well.. that's it. I forgot which part that shown the black haired guy but the important scenes are what I just told you. I'm sorry if the upcoming translation is a little diffeent from what I told you. The kanji are seriously made my head in pain.
So I re-checked the pages in my PC.......
And yep I think they are only roommates.... but Kaji maybe did has a thing about the black haired guy. He once said to Ritsuka 'I fell in love with a guy in the past' so maybe Kaji already gave up on the black haired guy.
In vol 2 page JP raws page 62, there is a conversation when the black haired guy said "haha, accompany me (playing for) duo violin in the evening then."
Kaji answered, "play the violin with your new boyriend."
"I won't play with him. Because I just like his face."
So yeah maybe they are only roommates. But because there are no more scene showing them together... I can't say much about their relationship. The only clear part is, in vol 2 there is a page (page 67) with the title 'The pleasant life with same store guy'. So.... they work in the same place maybe....
Because the vol 2 focused on what happened between Mafuyu and his past relationship with Yuki.
Yeah, I read that part too and I think Akihiko talks about how before his first relationship he thought love was something soft and gentle. Then he remarks that after his first love he realized it was a force that tears and rips you apart- I'm assuming that relationship with the violinist did NOT end well...
I also read some of chapter 12 which focuses a bit on Akihiko and Haruki.... and found some spoiler-ish stuff
Kaji wanted to try tying up Haruki's hair so he let him. He comments that it's gotten long and Haruki thinks of when he started growing it out. It flashes back to a year and a half (?) before where Haruki's hair kinda looks like Shinobu's from her other manga Links. Basically their eyes met and he felt a shudder go through him. Since then he's been growing his hair out after he came to like Akihiko in some resemblance of a continuous prayer.
So I read vol 2 of JP raw and hell yeah I cried. I'm not going to tell you all spoiler btw
- yuki (mafuyu's ex) was fighting with mafuyu, telling him that without mafuyu he couldn't live , mafuyu said to yuki 'well, can you die for me?' (And damn he really died)
-uenoyama kissed mafuyu (yup. Uenoyama is the seme. Mafuyu is purely a uke), saying he did well singing his song
- mafuyu admitted he loves a new person, and it's uenoyama.