Karin is a character from The Legend of Zelda: Breath of the Wild. She is a Hylian living at Hateno Village in the East Necluda region of Hyrule. She is the daughter of Clavia and Reede who lives in the house with the Goddess Statue.
If Link talks to her she tells him that she saw a Sheikah girl at the Hateno Ancient Tech Lab. It is later revealed the child she saw was actually the lab's 120 year old director Purah who had accidently reverted to a six year old after a mishap with an experimental de-aging Rune, mentioned by Purah in her diary. Purah's Diary states that she was spotted by one of the Hateno Village while attempting to relit the furnace that powers her lab and Karin's story implies she was the child that Purah was referring to. Though she told her father about the Sheikah girl she saw, but he did not believe her, though some of the villages children did and have been spying on the lab ever since in the hopes of catching a glimpse of her, forcing Purah to stay in her lab. It is implied that Karin is the author of the Girl's Notebook found within her house.
On rainy days, Link can find her inside her house reading a book. If Link looks closely at the book he can see an illustration depicting a swordsmen riding a horse wearing a blue tunic (resembling the Champion's Tunic) who resembles Link and may be storybook retelling of his heroics 100 years prior (as his heroics at Fort Hateno during the Great Calamity are known to the people of Hateno Village). Link is unable to read the book himself and Karin makes no mention of what it is about.