Sengoku Rance

Sengoku Rance is all about the most perverted hero of a fantastical world. Feel free to use more adjectives to describe him: idiotic, silly, etc and etc… He journeyed to JAPAN in order to have his way with the ladies of this land, and ended up as the secret ruler of Nobunaga House. In the process of conquering JAPAN, he unwittingly play the dupe for an ancient demon sealed in this land just waiting to be freed. Nevertheless, be it either demons or hostile forces, none shall stand between Rance and his ladies.

The protagonist Nakuto, has his sights on becoming the "War God" aka the Champion of a gladiator style tournament with a twist. When Nakuto tries to enter this tournament, he learns that there's a special condition required for entering. He must partner with a beautiful woman along as collateral, and so by chance he finds his childhood friend, Hazumi in town worried for him. Since he has no other choice he enters Hazumi as his partner. Much to Nakuto and Harumi's horror they learn of the reason for the female partners. Winners of these tournament matches can do whatever they so please to the losing opponent's partner for a whole day.