Miko: Multiverse Crossover, from the Start with the Divine Blade Murakumo and Sun Breathing!

Bai Yu transmigrated into a fused slice-of-life world crawling with evil spirits. He'd thought the world was already weird enough.

But he never expected Sona Sitri to show up, too.

What? This is the High School DxD world?

Are there evil spirits everywhere because Hades, the god of the underworld, mysteriously vanished, the underworld blew up, and the System developed a bug?

Well, that's... reasonable?

Okay, yeah, it is.

Bai Yu could only sigh. Since he couldn't lie flat, he had no choice but to get stronger.

Fortunately, Bai Yu obtained a Sign-In System. From the start, he signed in and received the divine blade Muramasa and the Sun Breathing technique.

Later, he even signed in character templates for Izayoi Sakamaki, the Three-Headed Dragon, and others, gradually becoming invincible.

P.S. This is a crossover world. The slice-of-life side includes Miko, A Certain Someone, The Quintessential Quintuplets, Gabriel DropOut, Miss Kobayashi's Dragon Maid, To Love-Ru, and more. The supernatural side includes No Game No Life and So I'm a Spider, So What? Other series may be added as things develop. The crossovers won't be thrown together haphazardly and cause the power systems to collapse.

This novel and its characters are entirely fictional. Any resemblance is purely coincidental. Do not imitate.