|The Marui Family! The Good, the Bad, and the Fearsome! (Marui-ke! Yoi Ko Warui Ko Osoroshii Ko! 丸井家！ 良い子 悪い子 恐ろしい子！！) is the first episode of Mitsudomoe. It was aired on July 2, 2010.
Newly hired teacher Satoshi Yabe begins his job teaching class 6-3 and soon becomes aware of the terrible Marui triplets: Mitsuba, Futaba and Hitoha. When the triplets notice Yabe might have a crush on the new school nurse, Aiko Kuriyama, they purposely try to injure his groin in the hope that Kuriyama will like what she sees. When Yabe incidentally gets injured after running into Kuriyama, she confuses him for a fourth grader (she's blind without her glasses). Yabe gets the class a pet hamster, which Hitoha names Chikubi (Nipples) and becomes attached to it. When others start to play with her too much, Hitoha starts becoming defensive.