Riku Fukagawa

Riku Fukagawa is 15-year-old boy who lives in Tokyo. He can't remember anything about his family and claims that the only thing he remembered when he was found 5 years ago was his name. Riku has an uncanny urge to help people and all other living things in need. He also states that he couldn't even remember proper Japanese. One day after school he goes to a flea market. There he sees an out-of-the-ordinary character named Satsuki selling "goldfish" though what he is selling is clearly not goldfish. When one of the creatures tries to eat Futaba, a small half rabbit boy, he takes the translating book that Satsuki had to help translate. Riku's friends and Riku himself were shocked to find that Riku could understand the strange language. After that, Satsuki claims that he is Riku's older brother and that he came to take him back to the shop. When Riku helps Satsuki with a delivery because he thinks the load will be too much for Satsuki alone. He tells Satsuki that he came along because he thought the trip would help trigger his memories. Satsuki said it wouldn't because Riku had barely ever left his bedroom so he didn't have many memories of the town anyway. It is later revealed that Riku is a tsunagi (the ability to listen and free a holy spirit from its stone)Riku is the youngest Hiyokoya brother.

(Source: Wikia)