Chihiro Enomoto is a freshman at the prestigious Rikkyoin High School. The students of Rikkyoin are engaged in a year-long contest designed to determine which individuals will become the Student Council for the subsequent school year. At the start of the contest, lots are drawn. After that they are split into groups by thier numbers.
The competitions are staged between different groups, and because even one loss means that one's group is automatically eliminated from the Kujibiki, teamwork and cooperation is needed. The competitions appear to range from mental exercises to physical challenges, including a cooking contest, a swimming race, endurance tests against both extreme heat and cold, and an intense war game.
(it is only a 3 episode OVA )
Kujibiki Unbalance first made it's big debut in the anime Genshiken. So basically it was an anime within an anime. XD