Watching videos now, starting with ShoutaaaAH! Is he actually crying?! ... Oh, he faked it. XD He seems to be used to using people. Guess that explains the "Filial Piety" thing listed as a hobby... He also didn't seem to take much seriously.
Hokuto up next. His voice reminds me faintly of Itsuki Koizumi. I can't quite follow what happened as well as the last video, even with the visual aide. As far as I can tell, he did something to make Hibiki sad/mad, made Takane mad, and Chihaya... can't tell. He did seem to think he could charm any girl, though.
Touma now... I think the girls were talking about being idols or something? Stuff they were good at? I dunno. I heard "dansu" in Hibiki's dialogue, before Touma seemingly riffed on her, and "uta" or something in Takane's dialogue when the music note came up, so I can only guess that Touma was making fun of them/being a general jerk. I also found that part towards the end on. "Green soda" or something? It made Hibiki laugh and say "kawaii", that's all I know. It seems Touma has some unexplored depths beyond the whole "intense rivalry" thing...