Kage No Jitsuryokusha Ni Naritakute! Wiki

An isekai light novel series written by Daisuke Aizawa and illustrated by Tōzai. It began serialization online in May 2018.

The story is about a boy in modern-day Japan who desires to be a mastermind who exerts power from the shadows, but he gets hit by a truck (or, more accurately, chooses to be hit by one, judging his best chance to achieve his goal is to die and gamble on reincarnating in a world that has magic) and dies. He is reborn in a fantasy world as Cid Kagenou, where he makes up a story that this world is secretly run by the Cult of Diablos, and his secret organization, "Shadow Garden", are the only ones that can fight them. However, it turns out that unbeknownst to him, this story is actually true. He continues fighting the Cult of Diablos under the alias Shadow, completely unaware that he is involved in a complicated power struggle.