Read manga: Seishun Forget!

manga
Summary:

"Live with Sincerity" is Natsuki Taiyou's motto. It's first day of high school and Taiyou was heading to a school and Taiyou meets Hinata during the way there. He fell in love at first sight and suddenly confessed to her. Her answer was yes and she runs away without saying who she was, but it turns that she was her classmate. Taiyou felt a destiny between them. However, on the next day, she doesn't remember who he is. why could it that be...?