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 126 year old director Purah who had accidently reverted to a six year old after a mishap with an experimental anti-aging Rune, mentioned by Purah in her diary. Purah's Diary states that she was spotted by one of the Hateno Village children 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 two village boys Azu and Sefaro 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 which contains a recipe for Pumpkin Stew indicating Karin likes to cook it to surprise her father Reede. When spoken too he mistakes Link for Azu and Sefaro insisting she did see her before realizing her mistake. She apparently dislikes people doubting she saw a Sheikah girl though despite this she obeys the warnings to stay away from the lab. Purah however has remained hold up in her lab as a result of Karin spotting her to keep the villagers from finding out about her condition which Purah has hidden from her family, Robbie, and Jerrin though Robbie later learns about it from Link.
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.