A young man wakes up, only to find himself in a bed, in an unknown house, in an unknown place. A lovely girl enters. She says that her name is Ryuuna and that she is practicing the art of White Magic as a priest. However, the young man cannot remember anything. He cannot even remember his own name. Ryuuna says that he was found unconscious outside of the village, with a pendant lying nearby. There is just one name written there, his name: Seraphis. Also, there is a strange engraving on his hand. Who is he really? Illumina is a rather basic Japanese-style RPG. The party of the heroes walk over the top-down world map, visiting towns and descending into dungeons. With a few exceptions, the towns are displayed as identically-looking pictures of locations, with menu-based navigation, Wizardry-style. The random, turn-based battles are also first-person, but the dungeons have the same top-down view as the map. Playable characters belong to defined classes (such as Ryuuna being a priest with various white magic spells that can be leveled up). If any character is killed in a battle, it's Game Over. There are several scenes with nudity and sexual situations in the game.