Yatsushiro is a tomboy, who is considered rougher than the guys. She finds stairs a pain, so she jumps out of windows, and once when she couldn't figure out how to open a door, she destroyed it instead. Despite this, she does have a girly side, as she developed a crush on one of her fellow classmen. She has poor handwriting, but after a week of practice with Kouki Akune, her penmanship improves to a level where she is no longer embarrassed by it.   ~!Ten years later, Yatsushiro is a calligrapher.!~  (Source: Medaka Box Wiki)

Kurokami Medaka, a first year, is elected as Student Council President, and the first thing she does is establish a suggestion box, later dubbed by students the "Medaka Box". Medaka encourages students to submit any problem to the box without hesitation and promises to take on any issue from anyone. 
 
Since Medaka won the Student Council elections with a staggering 98% of the vote, she ends up as the Council's only member. She asks her childhood friend, Hitoyoshi Zenkichi, for help and he grudgingly agrees, becoming the Student Council's lowest ranking member. Soon Medaka recruits two more people to the Student Council, the former judo club member Akune Kouki as secretary and the current swim club member Kikaijima Mogana, on loan for 300 yen a day, as treasurer. 
 
Now the Student Council members spend their days solving the problems submitted through the Medaka Box, whether they be hooligans in clubs where they don't belong, girls who need help writing love letters or people who've lost their pets, gradually earning the respect and admiration of the entire school. 
 
Included chapters: 
Volume 15 contains the gaiden "Good Loser Kumagawa" (グッドルーザー球磨川); Jump NEXT (2011/12/26) 
Volume 22 contains the gaiden "Good Loser Kumagawa Final" (完結編).

When newly elected Student Council President Medaka Kurokami institutes her idea for a suggestion box where people can submit problems that need to be solved, she's expecting things like rescuing lost puppies and giving advice. What she and her best friend Zenkichi find instead, however, are the first hints of an unbelievable secret, and their school, Hakoniwa Academy, and Medaka herself are somehow at the very center of the growing maelstrom! As what seemed like an innocent past time turns into a dangerous game, Medaka and her recruits to the Student Council discover new depths to both themselves and their own unexpected abilities. And then things get really out of control! 
(Source: Sentai Filmworks)

Kenna Yatsushiro