Ep. 5: Sun and Nagasumi face a school staffed by Sun's family and gang posing as teachers.
Aired on April 30, 2007

Sun and Nagasumi begin their first day of school, unaware that the faculty consists of Sun's parents, Gōzaburō and Ren Seto, alongside the Seto Gang, all disguised as educators. Complications arise when Nagasumi's friend, Hideyoshi "Chimp" Sarutobi, develops romantic feelings for Sun. Consequently, Nagasumi is forced to endure a barrage of hostile actions from his new classmates, who are actually his father's associates. The narrative focuses on Nagasumi's struggle to navigate this dangerous environment while trying to survive the constant attacks orchestrated by the disguised Seto Gang members who are posing as teachers at their middle school.
Episodes
- Ep. 1 · Teenager Nagasumi Michishio marries mermaid Sun Seto after being rescued from drowning
- Ep. 2 · Nagasumi protects Sun's tail during their Bon festival date
- Ep. 3 · Nagasumi and Sun face an assassination trap on a deserted island.
- Ep. 4 · Sun and Maki move into Nagasumi's city home while he retreats to the attic.
- Ep. 5 · Sun and Nagasumi face a school staffed by Sun's family and gang posing as teachers.
- Ep. 6 · Mawari Suspects Sun Is a Fish After Water Spill Incident
- Ep. 7 · Nagasumi encounters Lunar Edomae, who reveals her mermaid form and seeks to enslave him.
- Ep. 8 · Nagasumi proposes a singing contest to resolve the escalating school conflict involving Maki.
- Ep. 9 · Kai Mikawa, an agoraphobic merman, challenges Nagasumi for Sun's hand in marriage.