is a Japanese light novel series written by Daisuke Aizawa and illustrated by Tōzai. It began serialization online in May 2018 on the user-generated novel publishing website Shōsetsuka ni Narō. It was later acquired by Enterbrain, who have published the series since November 2018.
A manga adaptation with art by Anri Sakano has been serialized in Kadokawa Shoten's seinen manga magazine Comp Ace since December 2018. A spin-off manga by Seta U titled was also serialized via Comp Ace from July 2019 to September 2023. Both the light novel and main manga have been licensed in North America by Yen Press. An anime television series adaptation produced by Nexus aired from October 2022 to February 2023. A second season premiered in October 2023.
Plot
A boy in modern-day Japan desires to be a mastermind who exerts power from the shadows, but in the process of training, gets hit by a truck and dies. He is reborn in a fantasy world as Cid Kagenou, where he maintains a perfectly mediocre appearance so as to not stand out and pursue his dream of manipulating from the shadows. One day, he stumbles upon an elven girl infected by a mysterious disease and cures her.
Cid makes up a story, explaining this world is secretly run by the Cult of Diablos, and his secret organization, "Shadow Garden", is the only one that can fight them. The elven girl, now named Alpha, joins this organization and begins recruiting new members. However, the stories Cid made up were actually true, but he believes it to be total delusion; which is ironically the delusion. Cid continues fighting the Cult of Diablos under the alias "Shadow", completely unaware that he is involved in a complicated power struggle.
Characters
Main characters
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Kageno is the main protagonist and a high-school student who dedicated himself into becoming stronger than a nuclear bomb. However after an accident where he was hit by a truck, he was reincarnated into another world where magic exists. In this world, he is the son of a noble family and uses the strong magical powers he gained from being reborn to secretly moonlight as the leader of the Shadow Garden, an organization that fights in the shadows against the , but he believes both organizations to be imaginary and their participants are simply role-playing. He desires to act like a 'mob' character and blend into the background, but he has chūnibyō tendencies, basing all his actions on whatever he believes would look coolest.
Cid's older sister, a skilled spellsword. She thinks herself as stronger than Cid and pushes him around, often acting aggressively towards him in the form of punching him and other forms of bodily harm when she finds herself annoyed by him. However, she does care about him to an obsessive degree, acting quite recklessly when she thinks her brother might be threatened. Not long after curing Alpha of her demon possession, Cid notices that Claire is showing signs of the same "possession". He cures her while they were doing physical training without Claire even knowing it. She later absorbs Diablos and becomes its host, but Cid thinks she is role-playing.
A haughty princess, she makes it her job to make Cid's life as annoying as possible. She and Cid previously dated as an act, but she developed genuine feelings for him while he was eager to end their relationship. Also, she is one of the only characters to have personally seen "Shadow" in action (outside of Shadow Garden members) but does not know that Shadow's true identity is Cid himself. / (#666)
The princess of the neighboring kingdom of Oriana, a country known for its art. She controversially took up the sword instead of traditional arts and became a transfer student at the Midgard Spellsword academy. She became the student council president and her swordsmanship at the academy was considered only second to the first princess of Midgar, Iris Midgar. She becomes known as "666" in later volumes of the light novel when she joins Shadow Garden after a series of traumatic events.