The main protagonist of the series that Ai secretly in love with. Such an easy-going guy when going out with Minoru with an interest of seeking any cute and beautiful girls in their records, resulted to have many rumors imaginable which is not related to him whatsoever but some of them clearly had the fact about him. He had no interest of dating anyone besides of the same class.   ~!He finally going out with Ai when Ai confess her feelings at the end of their date on Christmas Eve. As it progresses, Tsuyoshi finally fall in love with her and get married in a few years after Ai's graduation.!~

When Tsuyoshi rushed to school as usual, he found a girl who tried to help a kitten which couldn't get down from a tree. It was Minamizato Ai who had loved Tsuyoshi secretly for a long time.

Tsuyoshi Yamaguchi