I really like this aspect. Sure, anime in general is full of bishoujo who just happen to be beautiful, but with Chihaya, and a series like this, it feels different. Like I said in an earlier post, she has the background to look like a supermodel and, again in a show like this, she has to do something do have those looks and not look like some karuta otaku. Yet, apart from looking like that at least partially consciously, it doesn't seem to matter to her at all, which makes it so great. The constrast is exhilarating.
I'm quite satisfied with Arata's reason and how it solved itself. He had been a total loner until he befriended Chihaya and Taichi, so going back to this small town he likely depended on the grandpa to have any like-minded company. Yet with the geezer gone, he was again alone yet this time with the experience of what it is to not be alone. It's very spychologically plausible to make all the wrong choices under such circumstances and sweve off to undesirable paths requiring an outside force to return from. Basically nothing more than a small reminder he's not alone after all.
I have no doubt Arata will still kick ass once he gets the rust off.