It is the start of Takatoshi Tsuda's second year as the put-upon vice president of the student council and his sister Kotomi is entering school as a first year. New friends and double entendres are made. (Source: ANN)

They say that the more things change, the more they stay the same, and those words could not be more true for the student council of Ousai Private Academy. Though an entire year has passed—bringing the senior members to their final year of high school—not much has changed. President Shino Amakusa is just as perverted as ever, Secretary Aria Shichijou still refuses to put on a pair of panties, Treasurer Suzu Hagimura has yet to grow an inch, and Vice President Takatoshi Tsuda is still stuck as the straight man to their crazy antics. Of course, limiting the fun to a four-way might get a little stale; although the group still messes around with the Judo Club and the Newspaper Club, more girls have come to get in on the excitement. Takatoshi's sister Kotomi, a new student at Ousai, is as perverse as the president, while Uomi, the aloof student council president of the nearby Eiryou High School, fits right in with the insanity at Ousai. With loads of absurdity and sexual humor that keeps on coming, Takatoshi needs to harden up if he is going to keep up with all the madness around him. [Written by MAL Rewrite]

OVAs of Seitokai Yakuindomo* which were either bundled with the limited editions of the manga volumes or as standalone OVAs.

Ousai Academy was originally an all-girls high school. Due to the declining birth rates in recent years, it was converted into a co-ed school. The first year male students would find themselves surrounded by girls and unfortunately, Tsuda Takatoshi is one of them. What's worse, he gets scolded on his first day by the student council president Shino Amakusa, which did not give a good first impression of him. Tsuda also meets the other student council members while getting scolded, and in the end, he gets late for class. As an apology for ruining his morning, Shino lets him join the student council for various of "reasons" and he accepts it, or rather, he's forced to accept. Thus begins his days as Tsuda soon realizes that he's the only normal student in Ousai Academy...