is a Japanese light novel series written by Yasukiyo Kotobuki and illustrated by Johndee. It began serialization on the user-generated novel publishing website Shōsetsuka ni Narō in February 2016. It was later acquired by Media Factory who began publishing it under their MF Books imprint in September 2016. A manga adaptation illustrated by 888 began serialization on Kadokawa's ComicWalker manga website in April 2018. A second manga adaptation illustrated by Maneki titled The Diary of a Middle-Aged Teacher's Carefree Life in Another World began serialization on Square Enix's Manga Up! manga website and app in October of the same year. An anime television series adaptation produced by Yanchester is set to premiere in January 2027.
Plot Satoshi Osako, a middle-aged man, loses his job and spends his days immersed in an online game, becoming a top-ranked player. Upon defeating the game's final boss, he is killed in the real world and reincarnated in a fantasy world as his in-game character, the powerful mage Zelos Merlin, retaining all of his abilities and knowledge.
After awakening in a dangerous forest, Zelos uses his overwhelming power to survive and begins traveling through the new world. Despite possessing extraordinary magical strength, he wishes to live a quiet and uneventful life. However, his abilities quickly draw attention when he rescues an elderly nobleman from bandits. Impressed, the man asks Zelos to become the private tutor of his granddaughter, Celestina van Solistia, a noble girl who is unable to use magic. As Zelos takes on the role of teacher, he becomes involved in the affairs of the nobility, all while continuing to seek a peaceful life.
Characters
Media Light novel Written by Yasukiyo Kotobuki, The Diary of a Middle-Aged Sage's Carefree Life in Another World began serialization on the user-generated novel publishing website Shōsetsuka ni Narō on February 7, 2016. It was later acquired by Media Factory who began releasing it with illustrations by Johndee under their MF Books light novel imprint on September 23, 2016. Twenty-one volumes have been released as of April 2026. The light novels are licensed in English by J-Novel Club.
A spin-off light novel series, titled Arafō Kenja no Isekai Seikatsu Nikki Zero: Sword and Sorcery World, began publication under the same imprint on August 25, 2023.
Volumes
Arafō Kenja no Isekai Seikatsu Nikki Zero: Sword and Sorcery World
Manga A manga adaptation illustrated by 888 began serialization on Kadokawa's ComicWalker manga website on April 25, 2018. The manga's chapters have been collected by Media Factory into nine volumes as of September 2026.
A second manga adaptation illustrated by Maneki, titled The Diary of a Middle-Aged Teacher's Carefree Life in Another World, began serialization on Square Enix's Manga Up! manga website and app on October 16 of the same year. The second manga's chapters have been collected into eighteen volumes as of June 2026. The second manga is published digitally in North America by Square Enix via their Manga Up! Global app.
A manga adaptation of the spin-off series, illustrated by Piyoko Hatori, began serialization on Frontier Works's FW Comics Alter manga website on December 15, 2025.
Volumes
The Diary of a Middle-Aged Teacher's Carefree Life in Another World
Anime An anime television series adaptation was announced on April 22, 2026. The series will be produced by Yanchester and directed by Takayuki Inagaki, with Hiroko Kanasugi handling series composition and Mariko Fujita designing the characters. It is set to premiere in January 2027.
Reception By April 2022, the series has over 2.2 million copies in circulation.
Notes
References
External links at Shōsetsuka ni Narō at ComicWalker at Manga Up! at Gangan Online