Kenkō Zenrakei Suieibu Umishō

• Ja Kanji — ケンコー全裸系水泳部 ウミショー • Genre — Romantic comedy

• Type — manga • Author — Mitsuru Hattori • Publisher — Kodansha • Imprint — Shōnen Magazine Comics • Magazine — Weekly Shōnen Magazine • First — July 13, 2005 • Last — April 23, 2008 • Volumes — 9

• Type — tv series • Director — Kōichirō Sōtome • Writer — Mamiko Ikeda • Music — Yasumasa Satou • Studio — Artland • Network — Tokyo MX, TVS, Chiba TV, TV Aichi, TVO • First — July 4, 2007 • Last — September 26, 2007 • Episodes — 13

• Portal — yes Healthy All-nude Swim Team Seacats Commerce High is a Japanese manga series written and illustrated by Mitsuru Hattori. It was serialized in Kodansha's manga magazine Weekly Shōnen Magazine from July 2005 to April 2008, with its chapters collected in nine tankōbon volumes. A 13-episode anime television series, produced by Artland and directed by Kōichirō Sōtome, was broadcast from July to September 2007.

Within the Kanagawa prefecture lies the seaside city of Umineko. There, Kaname Okiura, a student in his second year of high school, attends Prefectural Umineko Commercial High School, or Umishō for short. He is also the manager of the high school swim team though he himself does not know how to swim. In fact, he is afraid of the water stemming from an incident which occurred some years ago. While he was at the beach, he had nearly drowned when a "mermaid" pulled him under the water. He joined the school's swimming club in order to learn how to swim, but the club is filled with weirdos, who do not teach him swimming. One day, a floating house arrives at the shores of Umishō bearing two persons. One of these is a cheerful, sunny, happy-go-lucky girl named Amuro Ninagawa, a transfer student, and the other is her father. Her incredible swimming speed makes her an instant hit with the swimming club, but Kaname is surprised, as she reminds him of the mermaid he saw only once in his early childhood. After her floating house is destroyed during a storm she moves to Kaname's house. The fictional island of Onoshima, where the series is set, is modeled on the real island of Enoshima in Fujisawa, Kanagawa.

• Amuro Ninagawa • Aki Toyosaki • Amuro Ninagawa is a second-year transfer student at Umishō High School, originally from the Daito Islands in Okinawa. A naturally gifted swimmer accustomed to open-water swimming, she struggles with competitive pool events due to unfamiliarity with regulations and confined spaces—once colliding with the wall mid-race. Her unconventional behavior includes a preference for swimming nude, which she does unselfconsciously, particularly around Kaname Okiura. Despite her raw talent, adapting to structured competitions remains a challenge. • Kaname Okiura • Toshiyuki Toyonaga • Kaname Okiura is a second-year student and manager of the Umishō swim team. Traumatized by a childhood encounter with what he describes as a mermaid, he developed a fear of swimming that begins to fade after Amuro Ninagawa's arrival. While frequently exasperated by her unpredictable behavior, he gradually develops romantic feelings for her, though he often denies them. • Momoko Orizuka • Hitomi Nabatame • Orizuka is a third-year student and vice-captain of the Umishō swim team. As the most disciplined and level-headed member, she frequently serves as the straight man to her teammates' antics, particularly clashing with Ikamasa's irresponsible behavior. Her no-nonsense attitude and strong leadership help maintain order within the team. • Maki Ikuta • Ai Shimizu • A first-year student at Umishō High School, nicknamed Makio. Frequently mistaken for a middle schooler due to her petite stature, she remains a novice swimmer who receives instruction from Kaname Okiura while training with the team. • Masa Ikariya • Makoto Yasumura • The third-year captain of the Umishō swim team, nicknamed Ikamasa. Known for his muscular physique and eccentric behavior, he frequently irritates teammates with his obsession with shaving body hair and preference for revealing swimwear. His antics often disrupt team activities. • Mirei Shizuoka • Yukari Fukui • Shizuoka is a second-year student at Umishō High School. While admired for her swimming prowess—having nearly won the Kantō Tournament's 200-meter event—she exhibits paradoxical behavior: intensely self-conscious when observed, yet privately promiscuous, wearing revealing lingerie and collecting phallic objects like kokeshi dolls. This trait mirrors her parents' overt sexuality. Though displaying possible romantic interest in Kaname Okiura, her feelings remain ambiguous. As the granddaughter of the Shizu Group's founder, her background contrasts with her timid demeanor. • Maaya Nanako • Sayuri Yahagi • Maaya Nanako is a first-year transfer student, a competitive swimmer and model who joins Umishō to pursue her childhood crush on Kaname Okiura. Viewing Amuro as a romantic rival, she frequently clashes with her. Distinctive for her small fang and custom swimsuit, Maaya resents larger-breasted teammates like Amuro and forms an "Alliance" with Makio to address their shared insecurity about breast size. • Kise Sayane • Ryōko Shintani • Sanae is a third-year student and co-founder of Umishō's swim team, as well as Momoko Orizuka's childhood friend. Known for her mischievous behavior, she frequently causes trouble for others and fabricates stories both to tease teammates and attract male attention.

Written and illustrated by Mitsuru Hattori, Kenkō Zenrakei Suieibu Umishō was serialized in Kodansha's manga magazine Weekly Shōnen Magazine from July 13, 2005, to April 23, 2008. Kodansha collected its 129 chapters in nine tankōbon volumes, released from January 17, 2006, to June 17, 2008.

A 13-episode anime television series produced by Artland, directed by Kōichirō Sōtome and written by Mamiko Ikeda, aired on Tokyo MX, Television Saitama, Chiba TV, TV Aichi and TV Osaka, from July 4 to September 26, 2007. The opening theme is "Dolphin☆Jet" by Ayane, and the ending theme is "Splash Blue ~ Taiyō to Remonēdo" by Ayumi Murata.

An internet radio version of the anime series, Kenkō Zenrakei Suieibu Umishō: Junbi Undō, was first streamed on the Japanese websites Ōnsen and BEWE from May 16 to June 27, 2007. A continuation, Kenkō Zenrakei Suieibu Umishō: Natsu!! Honban, began streaming on July 4, 2007. The first version of the series featured Hitomi Nabatame, voice actor of Momoko Orizuka, while the continuation featured Nabatame and Aki Toyosaki, voice actor of Amuro Ninagawa.

A video game developed by 5pb. Inc., titled Umishō, was released for the PlayStation 2 on November 22, 2007.