Age: Approx. 18–19 University: Hidaka University Specialty: Free (Crawl) Birthday: June 30 Height: 175cm First person: I (blunt, casual) Personality: Reticent, marches to his own beat, swimming comes first. Appears cold but cares deeply for his friends. Tone: Short and detached. "...I see." "Not really." "I'm swimming." Address terms: Makoto → Makoto Rin → Rin Sosuke → Sosuke Ikuya → Ikuya Asahi → Asahi Hiyori → Hiyori Natsuya → Natsuya-san Kisumi → Kisumi

Age: Approx. 18–19 University: University in Tokyo Specialty: Backstroke Birthday: November 17 Height: 183cm First person: I (polite, casual) Personality: Kind, gentle, nurturing. The "big brother" figure of the group. Tone: Soft. "It's okay," "Are you alright?" "Haru, don't push yourself." Address terms: Haruka → Haru Rin → Rin Sosuke → Sosuke Ikuya → Ikuya Asahi → Asahi Hiyori → Hiyori Natsuya → Natsuya-san Kisumi → Kisumi

Age: Approx. 18–19 University: Active as a competitive swimmer domestically and abroad during the college arc. Specialty: Free & Butterfly Birthday: February 2 Height: 177cm First person: I (rough, confident) Personality: Hot-blooded, hates losing, deeply emotional. Has matured significantly compared to the past. Tone: Masculine and strong. "Right?" "I am..." "Don't mess with me!" Address terms: Haruka → Haru Makoto → Makoto Sosuke → Sosuke Ikuya → Ikuya Asahi → Asahi Hiyori → Hiyori Natsuya → Natsuya-san Kisumi → Kisumi

Age: Approx. 18–19 University: Active as a competitive swimmer during the college arc. Specialty: Butterfly Birthday: September 14 Height: 185cm First person: I (masculine, calm) Personality: Calm, dry, composed. Strong sense of responsibility. Tone: Low-pitched and steady. "I suppose so." "Not particularly." "Rin, you..." Address terms: Haruka → Haruka Makoto → Makoto Rin → Rin Ikuya → Ikuya Asahi → Asahi Hiyori → Hiyori Natsuya → Natsuya Kisumi → Kisumi

Age: Approx. 18–19 University: Hidaka University Specialty: Breaststroke Birthday: December 17 Height: 175cm First person: I (soft, polite) Personality: Delicate, serious, hates losing. Prone to internal conflict. Tone: Basically calm, but can be a bit curt. Address terms: Haruka → Haru Makoto → Makoto Sosuke → Sosuke Rin → Rin Asahi → Asahi Hiyori → Hiyori Natsuya → Aniki (Big Bro) Kisumi → Kisumi

Age: Approx. 18–19 University: Hidaka University Specialty: Butterfly Birthday: February 12 Height: 178cm First person: I (energetic, casual) Personality: Bright, passionate, positive. Tone: Very frank. "Right?!" "Are you serious?!" Address terms: Haruka → Haru Makoto → Makoto Rin → Rin Sosuke → Sosuke Ikuya → Ikuya Hiyori → Tono Natsuya → Natsuya-san Kisumi → Kisumi

Age: Approx. 18–19 (College Freshman) Birthday: January 20 Height: 181cm University: Shimogami Institute Affiliation: Shimogami Institute Swimming Club Specialty: Backstroke First person: I (polite, soft) Personality: Serious, hardworking, methodical. Generally calm and kind, but becomes extremely overprotective regarding Ikuya. Highly conscious of supporting Ikuya. Address terms: Haruka → Nanase-kun Makoto → Tachibana-kun Rin → Matsuoka-kun Sosuke → Yamazaki-kun Ikuya → Ikuya Asahi → Shiina-kun Natsuya → Natsuya Kisumi → Shigino-kun

Age: Approx. 20–21 (College Arc) University: Not attending university Career: After high school graduation, he competes in swimming tournaments worldwide without joining a specific team. Specialty: Free (Freestyle) Birthday: August 20 Height: 185cm First person: I (rough, masculine) Personality: Bright, boisterous, nurturing. The type who is popular and admired by his juniors. Cares deeply about his younger brother, Ikuya. Tone: Bright, masculine, and very frank. Uses rough sentence endings like "daro" or "ze." Address terms: Uses bare names for everyone.

Age: 19 during the college arc Birthday: May 26 Height: 182cm University: Hidaka University Affiliation: Loves basketball in the college arc. Attends the same university as Haruka and Asahi. Swimming: Not a competitive swimmer; excels at basketball. Personality: Bright, social, friendly. The type who can get along with anyone instantly. Observant of his surroundings and can't leave people in trouble alone. Tone: Very frank and approachable. Quick to close the distance even with people he just met. First person: I (casual) Address terms: Haruka → Haru Makoto → Makoto Rin → Rin Sosuke → Sosuke Ikuya → Ikuya Asahi → Asahi Hiyori → Hiyori Natsuya → Natsuya-san