The Misadventures of the Isekai Ocean Hero

Achievement Unlocked: "Harem Prince". Mate with a member of the opposite sex for the fiftieth time, you stallion you!

Reward: +50 Points to Endurance and Stamina. +10 Points to Charisma.

Kaito always had a rush of dopamine whenever he unlocked something. Coming down from the high of their love-making were two of the castle maids -- Nagi and Erika -- who were using his abs as a pillow. They were completely naked, their bright-blue mermaid tails rubbing against his legs.

Kaito was just an average nobody before the Submariner Kingdom of Yonaguni had summoned him to their world. In times of crisis, all the lands of this strange world of magic and danger would each hold a ritual that would summon a hero from another world that would protect their kingdom from the incoming Hordes of Horror. Yonaguni were a demihuman kingdom, so imagine their shock when they summoned a human to their temple.

Kaito has yet to meet the other Heroes. He had learned of the existence of a Jungle Hero, a Volcano Hero, a Desert Hero and a Tundra Hero, and there were no doubt many more he would learn about. Being the Hero summoned in the Yonaguni's undersea temple, he was titled the Ocean hero.

What made the Heroes so powerful was that their actions made them more and more powerful the more they did it. It was like muscle-memory, magically enhanced to God-tier levels. When he first came to Yonaguni, he could barely swim and could only last a few minutes underwater before he had to come up for air. Now he could swim at the speed of a shark and he could hold his breath for up to ten hours, something that would be impossible for any other human.

What he wasn't expecting was for him to find himself in the beds of so many mermaids.

Apparently Yonaguni had a hit-or-miss relationship to all the various human kingdoms of this world, so it took a lot of convincing on Kaito's part to win all of them over, though thankfully being the Ocean Hero made him the exception to this. Not only that, but the various sea-dwelling demihumans that inhabited the kingdom were going through a mating period, and many of them were interested in mating with the Ocean Hero.

Kaito was **** at first. He was a virgin in his old life and he didn't know that many single girls to begin with, so when he kept finding various mermaids from all over the capital city would proposition him for sex.

He certainly enjoyed all the sex, made more and more easier as his Hero abilities adapted and made it easier for him to mate with them in the harsh environment of the ocean, but his Hero powers would also reward him for his sexual escapades with extra goodies.

Within his first week he had earned the skills "Lust" and "Mate Guardian". These abilities increased his base physical capabilities the more sex he had, and made him more proficient in weaponry in the presence of the opposite sex respectively.