To See That Smile, Just One More Time - S20.E431

Karin is caught within the Infinite Tsukuyomi and dreams of her past. She was born into the Uzumaki Clan and has the unique ability to heal anyone who bites into her. Driven out of her village, the Hidden Grass takes her in, only to use her for this ability. Karin has no choice but to endure constant suffering in order to survive. She is later chosen to enter the Chunin Exams, where Sasuke saves her life. Karin has never forgotten what he did for her—or his smile.