Kill Blue (Japanese: キルアオ, Hepburn: Kiru Ao) is a Japanese manga series written and illustrated by Tadatoshi Fujimaki. It was serialized in Shueisha's Weekly Shōnen Jump magazine from April 2023 to September 2025, with its chapters collected in thirteen tankōbon volumes. An anime television series adaptation produced by Cue is set to premiere in April 2026.
Juzo Ogami is a 40-year-old who works for the Z.O.O. assassin syndicate as their prized hitman. During a job taking out criminals working with the genetic manipulation company Mitsuoka Pharmaceuticals, Ogami is stung by a wasp that modifies his DNA, regressing his age to that of when he was 12. Unable to resume work as a hitman due to his stature, the head of Z.O.O. gives Ogami another assignment while they work on an antidote: attend a middle school the head's daughter is applying to and judge if it is safe. Ogami, due to having no formal education, turns out to love middle school, and must balance his time as a student and an assassin. He must also deal with Noren Mitsuoka, the heiress of Mitsuoka Pharmaceuticals, who may be the key to figuring out how to age Ogami back to normal.
The main protagonist. He is a 40-year old assassin who is aged back to 12-years old after being stung by a mysterious wasp during a mission. Initially, he didn't like the idea of going back to middle school, but he soon came to enjoy it. His skill with a handgun has earned him the nickname "Demon's Left Hand".
The main heroine. She is a middle school student and the daughter of Mitsuoka Pharmaceuticals founder. She is constantly hit on by other students, causing her to initially hate men, before befriending Ogami. She helps out her Uncle at his Ramen Shop, and wishes to takeover it when he retires.
Ogami's partner. Although not nearly as experienced as Ogami, he is skilled with technology, and has more skill in cooking and house care. He created the pair of glasses that Ogami wears that acts as a camera and radio for him.
Written and illustrated by Tadatoshi Fujimaki, the series was serialized in Shueisha's Weekly Shōnen Jump magazine from April 17, 2023,[7][8] to September 1, 2025.[9] The series' individual chapters have been collected into thirteen tankōbon volumes, released from September 2023 to December 2025.[10][11]
Viz Media and Manga Plus are publishing the series in English simultaneously with its Japanese release.[12] Viz Media began releasing the volumes digitally in July 2024.[13][14]
An anime television series adaptation was announced on September 1, 2025, the same day as the final chapter of the manga. It will be produced by Cue and directed by Hiro Kaburagi [ja], with characters designed by Miho Daidōji.[9] The series is set to premiere in April 2026 on TV Tokyo and its affiliates.[4]
The series was ranked seventh in the Nationwide Bookstore Employees' Recommended Comics of 2024 list.[32] The series ranked tenth in the print category at the tenth Next Manga Awards in 2024.[33]
Kaylie Fielden of Screen Rant felt the plot was unique among other hitman manga and praised the beginning chapters.[2] Robbie Pleasant of Multiversity Comics praised the artwork and characters. Regarding the story, Pleasant felt that it has some worrying elements concerning a possible romance between Ogami and Noren Mitsuoka but nonetheless handled them well.[34] Kara Dennison of Otaku USA described the series as "Case Closed with added violence".[35]
