Mizuki Asami  

, 朝見 水輝

Mizuki Tsukishima's cousin from their mother's side is Isamu Asami. He is a world-renowned mountain climber who travels around the world frequently. Due to his upbringing overseas, Mizuki has become an excellent climber as well. Although he wants to finish high school in Japan, he enrolls at Seishū and stays with the Tsukishima family. He is a kind-hearted and honest person who is popular among girls in Seishū. However, his interest lies only in Aoba Tsukishima, seeing Yūhei Azuma as his rival on her. Despite being part of the mountaineering club at Seishū, Mizuki often engages in solo climbing activities that exceed the expectations of the club's activities. He frequently climbs tall structures such as poles and school buildings without any equipment.