|Also known as||Nao-senpai|
|Age|| 14-15 (High☆Speed! Vol. 2)
|Affiliation|| Iwatobi Junior High School (former)|
Iwatobi Swimming Club (former)
Soufukan High School (former)
|Anime||High☆Speed！－Free! Starting Days－|
|Light Novel||Volume 2|
Nao Serizawa (芹沢 尚 Serizawa Nao) is a third year junior high student who debuted in the second volume of the light novel High☆Speed! written by Kōji Ōji. He is a minor character in High☆Speed！－Free! Starting Days－, Free! -Take Your Marks- and Free!-Dive to the Future-. He was a manager of the Iwatobi Junior High swimming club. He's currently studying Sports Medicine in college.
He has long grey hair with bangs, yellowish-green eyes and is relatively tall and is usually shown with a kind smile on his face. Since graduating Junior High he wears glasses and his hair is shorter.
Nao is somewhat like Makoto, inferring to their kind nature and such. They share a similar eye shape (more droopy and kind-looking). Nao is somewhat motherly, and he has a gentle and soothing personality. Nao is extremely empathetic, prior-known to understand what Asahi is going through when Asahi says to Nao that what Natsuya said about their relay. He also is a good listener, letting the person he's talking to spill out to him.
Nao Serizawa was a third year at Iwatobi Junior High School while Makoto and Haruka were freshmen. He was a manager of the swimming club and was responsible for giving guidance to the first years. Nao was also the library committee president in junior high as revealed in the light novel.
- Main article: Nao Serizawa/Plot
He was the one who coached Haru, Makoto, Ikuya and Asahi when they were first years in middle school.
In High☆Speed！－Free! Starting Days－, he is shown to have gone through an eye surgery. In Free! -Take Your Marks-, Natsuya says it's due to an eye injury. He also says that he wishes he could swim with Nao again someday, but he can't since Nao isn't allowed to swim.
- Main article: Nao Serizawa/Relationships
- In Free!-Take Your Marks-, it was revealed that he is now studying Sports Medicine in university.
- Before getting into swimming, he was into Aikido (one of the kinds of martial arts).
- He is the coach of Misaki Kuramoto in Free!-Take Your Marks-.
- His motif animal is a northern gannett.