Hiroyuki Seguchi

Tokyo Bay Water Police, formed to combat rising maritime crime in under-patrolled waters contrasting land's high-surveillance success, unites a fractured team of officers—a veteran leader, an ambitious transfer detective, and a skilled marine engineer—whose clashing backgrounds evolve into collaborative resilience as they solve coastal crimes and protect Tokyo’s waterways.

Long is a Taiwanese killer known for his sword skills. After Long fails a Tokyo mission, he moves to a small town where no one knows about him.

Hiroyuki Tachikawa is 28-years-old. He quits his job due to severe quotas and difficult relations. His girlfriend, Chieko Takanashi (Eriko Nakamura), also kicks him out. Hiroyuki Tachikawa then decides to go to the small port city of Tsuyazaki in Fukuoka Prefecture. There, he meets a 72-year-old woman, Fukuko Hanada. She doesn't know why, but she likes Hiroyuki Tachikawa and takes him to different places. The young man soon picks up on the meaning of happiness.

Toshiyuki and his wife, Chiyoko, run a store named “Fukunoya” in Fukuoka. They become friends with a takoyaki (octopus dumpling) stall owner named Tsuru and try to help her out, as does the rest of the kind-hearted community.

Based on the TV series from the same name, Mentai Piriri stars Hanamaru Hakata, the icon of Hakata, Fukuoka, alongside Yasuko Tomita, who both starred in the television show playing husband and wife respectively. With additional scenes not depicted in the original show.

Tokyo Bay Water Police, formed to combat rising maritime crime in under-patrolled waters contrasting land's high-surveillance success, unites a fractured team of officers—a veteran leader, an ambitious transfer detective, and a skilled marine engineer—whose clashing backgrounds evolve into collaborative resilience as they solve coastal crimes and protect Tokyo’s waterways.