Summer Anime “Mattaku Saikin no Tantei Tokitara” Opens with Heart-Pounding Daily Life of Ojisan Detective & JK Assistant! First Episode Preview Cuts
From the summer anime *Mattaku Saikin no Tantei Tokitara*, the synopsis and preview cuts have been released for the first episode, “Moto Meitantei Nagumo Keiichiro / Mashiro no Gaichu Taiji”, which begins airing on Tuesday, July 1, 2025.







*Mattaku Saikin no Tantei Tokitara* is a gag mystery based on the manga by Igarashi Masakuni, serialized in “Dengeki Maoh” and boasting a cumulative print run exceeding 900,000 copies. The story centers on Nagumo Keiichiro, a detective who once shone brilliantly as a high school prodigy but has now become an ojisan left behind by the times.
The narrative kicks off when Mashiro, a vibrant high school girl, suddenly shows up one day insisting on becoming his assistant. Thus begins the thrilling, heart-pounding (“dokidoki”) everyday life of an ojisan detective and his self-proclaimed unique and beautiful JK assistant who aspires to be a detective.
Episode 1 Synopsis: “Moto Meitantei Nagumo Keiichiro”

Nagumo Keiichiro, age 35. The genius who once made a name for himself as a high school great detective is now a dull, outdated ojisan detective. One day, Mashiro, a vibrant high school girl aspiring to be a detective, appears before him.
Episode 1 Synopsis: “Mashiro no Gaichu Taiji”

Thanks to the promotional posters Mashiro put up around town, the Nagumo Detective Agency receives a request for pest extermination. Mashiro charges into the “pest nest” on behalf of Nagumo, who is not good with insects.
The first episode of the summer anime *Mattaku Saikin no Tantei Tokitara*, “Moto Meitantei Nagumo Keiichiro / Mashiro no Gaichu Taiji”, will begin airing on July 1 (Tuesday) on TOKYO MX, Sun TV, KBS Kyoto, BS11, and AT-X. It will also have an advance, exclusive fastest distribution on ABEMA.
TV Anime “Mattaku Saikin no Tantei Tokitara” Series Overview
ON AIR
Airing from July 1 (Tuesday) on TOKYO MX, Sun TV, KBS Kyoto, BS11, and AT-X!
AT-X: Every Tuesday at 23:30~
[Repeat Broadcasts] Every Thursday at 11:30~ / Every Monday at 17:30~
TOKYO MX: Every Tuesday at 24:30~
Sun TV: Every Tuesday at 24:30~
KBS Kyoto: Every Tuesday at 24:30~
BS11: Every Tuesday at 24:30~
Mie Television: Starting July 9 (Wednesday), every Wednesday at 24:20~
*Broadcast dates and times are subject to change without notice.
Advance, exclusive fastest distribution decided for ABEMA!
ABEMA: Starting July 1 (Tuesday), every Tuesday at 24:00~
Sequential distribution planned for other sites.
STAFF
| Role | Name |
|---|---|
| Original Work | Igarashi Masakuni (*Mattaku Saikin no Tantei Tokitara* serialized in Dengeki Maoh) |
| Director | Kujo Rion |
| Series Composition | Ikeda Rintaro |
| Character Design / Chief Animation Director | Koga Isonori |
| Art Director | Kuwajima Takeshi (Kusanagi) |
| Art Setting | Narita Yoshiyasu (Kusanagi), Arai Kana |
| Color Design | Aihara Ayako |
| Prop Design | Eto Makoto |
| 2D Design | Kuramochi Misato, Masuda Saki (Asahi Production) |
| 3DCG | SANZIGEN |
| Cinematographer | Hasegawa Naho (Asahi Production) |
| Editor | Enokida Misaki (Editz) |
| Sound Director | Ebina Yasunori |
| Sound Effects | Kurahashi Hiromune (Otonarium) |
| Music | Kikutani Tomoki |
| Music Production | KADOKAWA |
| Animation Production | LIDENFILMS |
MUSIC
Opening Theme Song: “Suffer” by Okazaki Taiiku
Ending Theme Song: “GORI☆GORI Feez e-Girl!!” by Mashiro (CV: Hanazawa Kana) VS Yukai na Ojisan-tachi (CV: Sugita Tomokazu)
CAST
| Character | Voice Actor |
|---|---|
| Nagumo Keiichiro | Suwabe Junichi |
| Mashiro | Hanazawa Kana |
| Asunaro Yuu | Yamaguchi Tomohiro |
| Kazamaki Hana | Hirano Aya |
| Nezu Taro | Kawanishi Kengo |
| Hoshino Azuha | Fairouz Ai |
| Fuu-chan | Watada Misaki |
| Kerberos | Horii Chado |
| Mimisaka Souya | Kase Yasuyuki |
| Chichikubi Shishoku Ojisan | Sugita Tomokazu |
| Juujimunege Ojisan | Sugita Tomokazu |
| Rope Daisuki Ojisan | Sugita Tomokazu |
| Coach | Iijima Hajime |
Related Link
Nakase Kotaro
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