While a great many otaku and aspiring loners everywhere have grandiose dreams and delusions of becoming the archetypical hero, Haruto Sekiwa had never exactly been that type.
You may hear about saving fantasy worlds and romancing all of the cute, totally not abnormally proportioned girls. Well, Haruto had a relatively simple dream—revolutionizing the modern bathing industry. He could never resist a nice, hot bath.
This is why when he fell in the bath and managed to die on the spot, Haruto was pleasantly surprised to finally be one with his dream. He finds himself in a bath. Breaking all possible rules of physics and completely disregarding common sense, he managed to seemingly reincarnate. It sounds like he was paying off whatever Gods that ceased to exist until then.
However, his peacefulness was soon shattered by his ability to recognize basic patterns and tropes.
Haruto: "Are those... horns?"
He stares at the distorted door leading into the bathroom, making out a womanly shape in the shadows. This sets off every possible alarm bell in any human who's managed to watch enough bargain bin harem anime.
Haruto: "Are you sure this isn't that thing where the tsundere walks in on you and gains the strength of a thousand buff ghosts?"
He awaits his demise at the hands of a blonde, twin-tailed loli as the door slides open.
???: "Damn, being a generic head of state sure is hard work. I'm glad we've invented magic baths here. Truly, this is the best timeline."
Haruto was then faced with quite possibly the most fitting candidate for Demon Queen in a fantasy world. He runs down his mental list of traits he has for characters of this archetype.
Slightly darker skin than the average paper-colored anime girl? Check.
Obviously menacing features like horns or spikes? Check.
Looks a little bit too much like an evil turtle king became a human girl? Check.
Haruto was prepared for the worst before the Queen filled the bath, and immediately started lathering herself with his... sodium hydroxide? Haruto had finally realized the title of the next bestselling isekai story. He had become the Demon Queen's bar of soap.
Haruto: "How meta can these trashy isekai stories get? Seriously, reincarnated as soap? What self-respecting author makes their reincarnated keyboard and reincarnated gaming PC suffer through that cringe-fest? I'd write a scathing criticism on how this is ruining an already oversaturated industry, but I'm currently a monologuing inanimate object. Curse you, irony!"