Rin Itoshiki is a supporting character in the anime and manga series Sayonara Zetsubou Sensei. She is the younger sister of the protagonist, Nozomu Itoshiki. Rin is known for her calm and quiet demeanor, often expressing herself in a reserved manner. She cares deeply for her brother and sometimes appears in the story to provide subtle emotional support. Rin's presence adds depth to the exploration of the Itoshiki family and the quirky, dark humor that defines the series.