Zecchou Skill "Onsen Souzou" de Yukemuri Harem wo Kizuku made: Hensei ga Todokottara Soku Dorei no Isekai Tensei! Akaji Ryokan Saiken Keikaku

Tono Jin, a former inn employee, is reincarnated from the modern world into another world and bestowed with cheat abilities. Excited about his first time in another world, Jin encounters Slime-kun for the first time. Slime-kun's attacks are incredibly powerful, contrary to his cute appearance. Jin tries to resist using his cheat abilities, but hot water simply comes out of his palm, dealing no damage whatsoever!? Jin is in a dire situation, and begs a female adventurer named Oralia, who happens to be passing by, to help him out, saying, "I'll do whatever you say!" She barely escapes with her life. However, Jin doesn't know at the time that he's chosen the wrong person to help him, and the true power of the skill he's been bestowed...! Use the ultimate skill, "Hot Spring Creation," that can make anyone orgasm and help rebuild the inn that's in the red!? A slightly erotic, otherworldly harem fantasy begins!

(Source: Futabasha, translated)