Yuu Haruna moved to Tokyo and started high school there because his parents were moved to America for business. He lives with his 3 sisters Hibiki, Maya, and Chitose. He uses Twitter often and posts about his life whenever he gets the opportunity. On his first day he meets Fuuka on the street where she bumps into him and falls over, with the way Yuu was standing with his phone in his hand checking Twitter Fuuka believes he was attempting to take a picture of her exposed panties while she was on the ground. She takes his phone and breaks it and they later find out they're in the same home room class the next day.
When Fuuka dies in chapter 37, he refuses to attend her funeral and instead waits for her at the park.