Masa Ikariya, nicknamed Ikamasa, is a third year student at Umineko Shōgyō High School and the captain as well as one of the founders of the school’s swimming club.
Masa has been swimming since elementary school, together with Taku and Momoko Orizuka. According to Sanae Kise he wanted to start a mah-jong club in high school, but could not find any other potential members. Then she and Momoko got him to join the swimming club.
Masa is tall and muscular, has dark hair and wears glasses. Most of the time he behaves like an idiot, rarely taking anything serious. For example he often wants to shave people or during a tournament he had a picture of his face attached to the front of his swimming briefs.
After the third year students quit the swimming club Masa stopped exercising and gained a lot of weight, which later on he lost again. Five years later he has opened a bar near his father’s restaurant.
He is most likely the club's best male swimmer and participates in 100 m and 200 m butterfly competitions.