Rin Itoshiki 糸色倫

Nozomu's younger sister, a seventeen-year-old ikebana master. When her name is written horizontally it resembles zetsurin ("unequaled"), which describes her exceptional talent in various skills; however, calling her zetsurin evokes her fury, as the word is often used as slang for sexual prowess.

She has revealed her willingness to marry out of the Itoshiki family in the hope of abandoning her unwanted name. Rin eventually transfers to Nozomu's school and becomes a student in his class, after which she frequently faces the readers/audience with her backside (in a parody Shin-chan, who is also voiced by Akiko Yajima). She also happens to own a chocolate factory.