| Ja Kanji: | なぜ僕の世界を誰も覚えていないのか？ |
| Ja Romaji: | Naze Boku no Sekai wo Dare mo Oboeteinainoka? |
| Genre: | Fantasy |
| Type: | light novel |
| Author: | Kei Sazane |
| Illustrator: | Neco |
| Publisher: | Media Factory |
| Demographic: | Male |
| Imprint: | MF Bunko J |
| First: | July 25, 2017 |
| Last: | August 25, 2020 |
| Volumes: | 9 |
| Type: | manga |
| Author: | Kei Sazane |
| Illustrator: | Arikan |
| Publisher: | Media Factory |
| Magazine: | Monthly Comic Alive |
| First: | February 27, 2018 |
| Volumes: | 11 |
| Type: | tv series |
| Director: | Tatsuma Minamikawa |
| Music: | Akiyoshi Yasuda |
| Studio: | Project No.9 |
| Licensee: | Crunchyroll |
| Network: | Tokyo MX, BS Asahi, Kansai TV |
| First: | July 13, 2024 |
| Last: | present |
| Episodes: | 6 |
| Portal: | yes |
is a Japanese light novel series written by Kei Sazane with illustrations by Neco. It was published under Media Factory's MF Bunko J imprint from July 2017 to August 2020. A manga adaptation illustrated by Arikan began serialization in Media Factory's Monthly Comic Alive manga magazine in February 2018. An anime television series adaptation produced by Project No.9 premiered in July 2024.
A war between five races for supremacy on Earth is won by humanity, led by the hero Sid. Suddenly, history gets overwritten so that Sid never existed, leading to humanity losing and becoming subjugated by the other races. All of this is witnessed by a boy named Kai, who is mysteriously unaffected by the alterations. In this new world, Kai finds that he never existed previously, so no one knows him. After meeting a mysterious girl named Rinne, Kai is inspired to become the hero himself and free humanity.
A manga adaptation illustrated by Arikan began serialization in Media Factory's Monthly Comic Alive manga magazine on February 27, 2018.[1] It has been collected in eleven volumes as of April 2024. The manga adaptation is published digitally in English on Kadokawa Corporation's BookWalker website.[2]
In July 2023, during the MF Bunko J Summer School Festival 2023 event, an anime television series adaptation was announced.[3] It is produced by Project No.9 and directed by Tatsuma Minamikawa, with scripts written by Satoru Sugizawa, and characters designed by Hiromi Kato.[4] While the anime received an advance screening on June 16, 2024 at the Grand Cinema Sunshine in Ikebukuro, Tokyo, it later officially premiered on July 13, 2024, on Tokyo MX and other networks.[5] [6] The opening theme song is performed by Unlucky Morpheus, while the multiple ending theme songs are performed in the following: the first is performed by Susu, the second is performed by Urbangarde, and the third is "Umbra" performed by Elfensjón.[6] Crunchyroll licensed the series.[7] Medialink licensed the series in East, Southeast Asia and Oceania (except Australia and New Zealand) for streaming on Ani-One Asia's YouTube channel.[8]
By July 2023, the series had over 700,000 copies in circulation.[9]