For instance, to me Ruka is a combo of Kozue and Yagami. And thank the FSM, the drunken-hijinks gang is considerably toned down (MI's irritated the stuffing out of me). Cool grandma who looks out for MC is definitely used to good effect.
But I hope we're not in for Umi all-but-kidnapping Chizuru and keeping her out all night to pressure her, this MC would probably try to kill himself by jumping off the second floor railing and break his arm.

And I really hope we're not in for an arc where Chizuru and Ruka misunderstand Mami and MC coming out of a love hotel.