MM! or えむえむっ! is a light novel series written by Akinari Matsuno and illustrated by QP:flapper, spanning 12 volumes from February 2007 to September 2010 including two side story volumes. It is however an incomplete series, as the author died on April 18 2011. There was also a manga adaptation by Issei Hyoju between September 2008 and February 2012, as well as a Drama CD adaptation on March 24, 2010. A 12-episode anime adaptation produced by Xebec aired between October and December in 2010, licensed by Sentai Filmworks.
MM! follows the story of Sado Tarō, a seemingly regular high school student who is actually a masochist, and one that's only sensitive to being abused by girls. He doesn't want to be a masochist as it causes him social and personal problems. His friend, Hayama Tatsukichi tells him to go to the Second Volunteering Club to help sort out his problems. There he meets Isurugi Mio (who calls herself God) and Yūno Arashiko, who also has an annoying problem she wants to sort out. High school antics ensue.
Sado Tarō (砂戸 太郎) is a masochist, and is the focus the series.