Noooo, not a sudden guy that shows up out of nowhere! It'd at least be a bit better if Tsukasa actually knew who he was, but... nope....
You know, stupid theory, but perhaps Tsukasa was that takoyaki shirt wearing "boy" that Washio fell in love with? Kotooka did mention that she looked a lot like a boy in the past... I don't think they even went to the same grade school, but, yeah, that's why this is a stupid theory.