I’ve Been Mentally Fighting Against The Strongest Evil Spirit Ever Since Birth (Insane Advantage), So My Magic Power Ended Up Going Over The Measurable Limit ~The Possessed Child’s Modest Path to Supremacy~

[Torka]

Alt titles: 生まれた直後から最強悪霊と脳内バトルしてたら魔力量が測定可能域を超えてました　～悪憑の子の謙虚な覇道～, Umareta Chokugo Kara Saikyou Akuryou to Nounai Batoru Shitetara Maryokuryou ga Sokutei Kanouiki wo Koetemashita ~Akutsuki no Ko no Kenkyo na Hadou~

Author: Nayuru Kouji
Artist: Katase Bono
Publisher: Kodansha
Volumes: 1 so far (released Dec 2025)

Synopsis: A mental battle against the strongest evil spirit just five seconds after being born! …And while he was doing that, his magic power ended up getting maxed out?! Shirakami Kai was reincarnated into an alternate Japan where monsters known as “Spirit Fiends” exist. But when he was born, for some reason, he was caught up in a ritual to summon the “strongest evil spirit.” A curse tried to kill his mother, after which the evil spirit went on a rampage, trying to take over Kai’s body. And while he continued to battle against the strongest evil spirit inside his head, he became an incredibly powerful entity without even realizing it?!

Comments: Just saw that a manga adaption was made of this and it’s surprisingly not bad? Main character dies and is reincarnated in a version of his world with evil spirits and exorcists, and manages to become super powerful by resisting the evil spirit implanted in him. It reminds me of Isekai Exorcist, somewhat.