In Lilina's travels through the land, she and her companions will come across all sorts of miscreants and monsters who would like nothing better than to subject them to any number of unfortunate, erotic fates. You'll be confronting them through a front-view perspective reminiscent of Earthbound/Mother or Dragon Quest. Each enemy also has a unique introduction that plays before they fight.
All the usual aspects of RPGs are here, with the typical stats being HP, Attack, Defense, Magic Attack, Magic Defense, Agility, and Luck. Two unique gauges are present, though: Lust and, depending on the class, Combat (CP).
Combat is rather straightforward. You gain CP as you attack and are attacked, and can then spend stored CP on special moves.

Lust is a bit different. It's essentially a "second" HP bar that fills up instead of depletes. Each character has a maximum Lust limit that increases as they level up. If one of your girls' Lust maxes out, she'll be unable to take it anymore and surrender to the enemy.
Lilina and Sinian don't have a Combat meter, but they can use magic. Magic doesn't use MP as in some games, because MP doesn't exist. Instead, spells each have a limited number of uses that are replenished when your party is fully restored or when you use the Meditate skill, which only Sinian starts the game with. Magic spells are much more varied than Combat techniques, but their users are much more frail than Combat specialists.
Generally, your fights will go much like any other RPG - you deplete the enemy's HP to win. What happens during said fights, however, is another story...