I'll Save the World Once I've Rated All the Monster Girls

"Mr. Chen Che, the Demon Lord's army has overrun the frontline fortress. As an SSS-rank hero, when exactly are you setting out?"

"No rush. I just got into the vampire progenitor's castle maid cafe, and my tea hasn't even gone cold."

"But the people of every race across the continent are counting on you to save them!"

"What the hell do I care if the world gets destroyed? I just want to finish this book, A Guide to the Customs of All Races, before I retire."

"...Wait, it looks like the Demon Lord's vanguard just blew up the catgirl hot spring west of town!"

"Damn it! Which blind bastard wrecked my happy place? Bring me my holy sword! None of the Demon Lord's army are getting out alive today!"

After transmigrating to a crossover fantasy world, he gets bound to the [All-Races Customs Review System]. As long as he experiences and publishes reviews of otherworldly races, he can draw wildly overpowered crossover skills, and even convert his review subjects' affection directly into attack power.

And so, the whole world goes completely off the rails.

The succubus queen trembles on her throne: "Stop hitting me! I'll help you get dressed and give you a massage right away!"

The crossover heroines all lose their composure one after another:

Roxy: "You said this was proper magic instruction. Why did it turn into a review of bathroom descaling?"

Miss Kaguya: "Explain this article, 'How to Get Your Tsundere Maid to Offer You Her Lap as a Pillow'!"