Hi, I'm one of your readers and the one that commented asking about the personality on the male teacher (I think he's a teacher, I have a bad memory) Just incase you don't remember me! Anyways, I have a few first names that might work so far and I'll put their meaning next to them!
Kazuhiko - harmonious boy
Kazou - Man of harmony (Since you said he expresses his feelings through the love of music)
Yoshio - joyful life (Because why not)
Kanji - Cold, Dignified (I think...)
Rin/Rinako/Rini/Ryn/Rynn - Cold Hearted (All of them have the same mean + I thought why not since He's a bit of a Tsundere)
And I'm still thinking of more that will go along the lines of his personality (Kinda) So if you don't choose any of these, You can easily just ask for more and if you want his name to have a certain meaning (As in it means music or life or purity etc. etc.) Feel free to message me and I'll try hard to find a good one!