Natsuya Kirishima

Ikuya's older brother. Height: 185 cm. Born on August 20. His specialty is freestyle. During middle school, he attended Iwatobi Middle School, served as the captain of the swim team, and was highly respected by everyone.

He was close to Ikuya, but he felt that if things continued as they were, Ikuya would always be chasing after him. So, he urged Ikuya to "broaden your horizons and make friends," and distanced himself from Ikuya when they entered middle school. Since then, their relationship became strained, and they often exchanged sarcastic remarks. However, after Ikuya understood the importance of friends, they reconciled.

After graduating from Iwatobi Middle School, he went on to Minato Fukan High School. After graduating from there, he did not join any team but participated in swimming competitions as a "prize hunter" while traveling the world. He met Rin, who was studying abroad in Sydney. After returning to Japan, he participated in a joint training camp with Iwatobi, Minato Fukan, and Samezuka Academy as an alumnus.

There, he advised Sousuke, who was unsure about undergoing surgery for his injury. His image is that of a tiger shark.