Kenji is just an ordinary college student. One day he was noticed by Senpai, and was asked to retrieve Senpai's personal belongings, which happened to be a bag of sex toys. On the way he met Mana-chan (a girl he liked), who after finding out what he was carrying told the supposed Man-Thot to be gone, and bounced out.

Wanting to explain the misunderstanding, Kenji chased after her, but gets plowed by JAV Truck-Senpai after he stops to bend down and pick up a fleshlight he dropped. Being the standard Isekai trash we all love to hate, once he died he wakes up on another world in a strange forest with only the clothes on his back, the vibrator wand in his hand, and all virginities intact.

Join Kenji on his journey as the Hero of this new world, one female orgasm at a time.

The year is 20xx, and Japanese men are a dying breed. At the end of World War III, Japan was hit by a Man-Bomb, which rewrote the DNA of Japanese men, weakening them and stripping them of their will to fight. Those that survived gave their lives to save their country. But the Spirit of Yamato still lives on... in the Japanese women!

This manga tells a story about new Demon Lord Vellmort XIII. Day after day he suffers from boredom, because all Underworld is already conquered by his predecessors, nobody (except maid Sarah) dares to oppose him and he is already sick of luxury food and jollifications with concubines. But some fateful day he has found a solution and together with Sarah has gone to conquer the Ground, populated by humans. Will he succeed in his plan or will he die by the hands of justice?