They have a good relationship. He supports Yuzu relationship with her lover, without knowing who that is. He does worry about her from to time to time.
They have a very casual relationship, with Matsuri being a regular customer in his cafe since she was little
They met each other during the summer trip, than met again after finding out they are arranged to be married to her. He did not know that Mei was an Aihara or that she's Yuz u's step-sister. But after finding out that Mei is Yuzu's lover he calls off the engagement to support their love.