Mitsudomoe

Mitsudomoe (みつどもえ, lit. Three Way Struggle) is a gag manga series by manga creator Norio Sakurai about the adventures of the Marui triplets in sixth grade and their newly hired teacher Satoshi Yabe as he falls in love with the school nurse. It's serialized in Akita Shoten Shōnen magazine Weekly Shōnen Champion since 2006 and the serial chapters collected into ten tankōbon. In July 2010, the manga was adapted into an anime series, running for 13 weeks. A second series, titled Mitsudomoe Zōryōchū! (みつどもえ 増量中！), aired between January 9, 2011 and February 28, 2011.

Story
Satoshi Yabe is just starting his new life as an elementary school teacher. Little does he know that in his assigned 6th year class, the law is made by the troublesome Marui triplets, Mitsuba, Futaba and Hitoha. The series showcases the everyday life of these sisters, their classmates and their unfortunate teacher.