The Eminence In Shadow (陰の実力者になりたくて!)

Storyline

Ever since he was a child, he wanted to become a shadowbroker, a person who operates in the shadows. He trained up his body, doing practically everything possible in the world, until one day on one of his training sessions, he encountered magic. However, this was not magic and was in fact, the headlights of a car. And so, he died. Even after reincarnating, the boy, now the son of a noble, Cid Kagenou, wanted to achieve his dreams. After rescuing a girl, Cid creates an elaborate plot about how he was the leader of an ancient organization, sworn to fight the Cult of Diabolos, so as to prevent said cult from resurrecting Diabolos. The girl swears her allegiance to Cid and so, he builds his organization, the Shadow Garden. Little does he know that his eighth-grader syndrome-induced story has actual basis in the world.