I'm tied up between Sylvie and Seika. I like Yuu a lot, but she doesn't interact with any other person besides Teppei much. The other two's bomb-stopping combo boosted their popularity a lot, and they're also much better at taking the initiative towards Teppei than Yuu. I can't blame her though, given her social status. To her, she's only allowed to do something if Teppei allows her to.