It all began very innocently: a beauty contest in a quiet Japanese town. The hero, an ordinary young man (default name Fukai Rei), is happy to look at pretty women. But everything goes terribly wrong. A huge demon appears, sending his minions and invading the town. Accidentally, the hero meets several angel-like girls with supernatural powers. They tell him that they were banned to live on the Earth for hundreds of years, but time has come for them to reunite and to fight the forces of darkness - naturally, under the hero’s guidance!
Super Erecto Taisen: S・EX is a strategy game with strong RPG elements. The player commands a party consisting of the hero and the angelic female fighters. The goal is to fight through several stages (marked on the map) in any order, defeating the occupying demonic forces. The characters move on the top-down battle field in round-based fashion, attacking when an opponent is on a nearby field. When attacked, the player has the choice of counter-attack or defense. Attacks are shown as small animated sequences at the bottom of the screen. Defeating enemies result in experience points and money, which can be spent to buy equipment for the player-controlled characters.