So the Nisekoi freshmen finally makes an official debut at Raku's school, and Haru makes her debut as the female MC of the episode. Yes, she made a cameo in the first season's ova and episode 6.
HaruHaru, as she is affectionately known and forgotten in the current Nisekoi manga chapters, is Kosaki's little sister. Having a major part in the season's opening will hopefully give her a fuller role than that of the manga. I'm guessing the author does not want her to upstage her older sister.
This episode revolves around Haru's antics and her attempt to defend her sister's honor against the villainous Raku - who has the biggest harem in the school par none. Namely, the school's top three beauties - Chitoge, Kosaki and Marika in that order. Or switch Tsugumi with Marika if you're a fan of big boobs.
We also see Paula, who became a classmate:
Very soon, the Onodera blood in her causes hijinks to occur - mainly in the form of seduction/attraction to Raku. And its true that all the female members of the Onodera family has a liking for him - Haru unknowingly at this stage.
Somehow or the other, Haru's skirt has a tendency to flip right in front of Raku, giving him a view of a pretty belly button and panties. And this happens during serious moments, like when Haru is declaring her incestuous lesbian sister off limits, spoiling the effect completely. Luckily she was wearing pants in episode 6.
Here's hoping that she might wear bunny panties sometime later.