is a Japanese light novel series written by Nigojà « and illustrated by Umibà Âzu. Media Factory have published the series since November 2019 under their MF Bunko J imprint. A manga adaptation with art by Mugiko has been serialized in Media Factory's manga magazine Monthly Comic Alive since May 2020. Both the light novel and manga are licensed in North America by Yen Press. An anime television series adaptation by ENGI aired from July to September 2021. A second season is set to premiere in October 2026.
Ever since he was a child, Kimihiko Kimizuka has attracted trouble. According to him, he was born with a condition that naturally attracts him to troublesome situations, such as being forced to join a flash mob while taking a leisurely walk, accidentally stumbling across an underworld transaction between drug dealers, and being at the site of crime scenes often enough to sometimes be considered a suspect.
One particular day in his third year of junior high, he was kidnapped and forced to carry a suitcase onto an international flight; on that flight, he met Siesta, a beautiful young woman who proclaims herself to be a "legendary detective". Forcefully made into her sidekick, Kimihiko helped her stop the plane from being hijacked, but not before Kimihiko discovered the existence of underworld organizations. After being constantly pestered, Kimihiko agrees to be Siesta's sidekick and for three years, they worked together, finding and solving an innumerable number of cases.
Now in his last year of senior high, Kimihiko is once again confronted by the ghosts of the past as he tries to solve new cases that fall into his lap. He is extremely bothered by the fact that he is called a detective; after all, the detective is already dead.
The idea of The Detective Is Already Dead started from a random sentence the author, Nigojà «, thought of one day. The sentence was "Is there a detective on the plane?", and later became the first sentence of the story.
The series is written by Nigojà « and illustrated by Umibà Âzu. Media Factory has published thirteen volumes since November 2019 under their MF Bunko J imprint. It is licensed in North America by Yen Press.
Its spin-off is written by Syusui Tsukimi, illustrated by Hanekoto, and supervised by Nigojà «. Media Factory has published two volumes since August 2023 under their MF Bunko J imprint. On February 28, 2025, Yen Press announced they had licensed the spin-off series.
Another spin-off is written by Hinachihoko, illustrated by Minori Chigusa, and supervised by Nigojà «. Media Factory published the novel in May 2024 under their MF Bunko J imprint.
Another spin-off is written by Shao Senlin, illustrated by Almic, and supervised by Nigojà «. Media Factory published the novel in August 2024 under their MF Bunko J imprint.
A manga adaptation by Mugiko was serialized in Media Factory's manga magazine Monthly Comic Alive from May 27, 2020, to October 27, 2023. It has been collected in six volumes. Yen Press also licensed the manga adaptation. The manga series covers the first and third volumes of the novel series.
A second manga adaptation by Poni titled was serialized in Monthly Comic Alive from January 27, 2021, to September 27, 2022. It has been collected in four volumes. The manga series covers the second volume of the novel series.
Its spin-off Toaru Meitantei to Joshà « no Love Com-deki Nichijà  (), illustrated by Moyashi Itame, has been collected in two volumes so far.
An art book is published by Kadokawa.
The 12-episode anime television series adaptation was announced on January 20, 2021. The series is animated by ENGI and directed by Manabu Kurihara, with Deko Akao handling the series' scripts, and Yà Âsuke Ità  designing the characters. Yuuyu, Naoki Tani, and Tatsuya Yano composed the series' music. It aired from July 4 to September 19, 2021, on AT-X and other channels, with the first episode airing as a one-hour special. Mary àJon-Yakitory performed the opening theme song, , while Kagura Nana performed the ending theme song, . Funimation licensed the series outside of Asia. Following Sony's acquisition of Crunchyroll, the series was moved to Crunchyroll. Muse Communication licensed the series in South and Southeast Asia, and streams the series on its YouTube channel (has been removed), iQIYI, and Bilibili and aired on Animax Asia.
It was announced that the VTubers Shirakami Fubuki and Natsuiro Matsuri of Hololive would have a cameo in the third episode of the anime. On July 14, 2021, it was announced that the anime would receive a German dub with the first dubbed episode airing on July 18 the same year. On October 2, 2021, Funimation announced that the series would receive an English dub, which premiered the following day.
On July 24, 2022, during the "Natsu no Gakuensai 2022" event for the MF Bunko J imprint, it was announced that the series would be receiving a second season. The staff and cast members from the first season are reprising their roles. The season was originally scheduled for July 2026, but was later delayed due to production issues. It is set to premiere in October 2026.
The first part of Ep.1, Ep.2 to Ep. 4, Ep. 10, and part of Ep. 11 to Ep. 12 cover the story of Vol.1 of the light novel series. The second part of Ep.1, Ep.5 to Ep.9, and part of Ep. 11 to Ep. 12 cover Vol.2 of the series.
The light novel series won the 15th MF Bunko J newcomer award in 2019.
The light novel series placed third and first in July and August 2021 respectively on the Oricon monthly light novel chart.
As of July 2022, the series has 1 million copies in circulation.