You play the role of Takuya Arima, a young student whose father, a historian who has conducted various researches, disappeared recently. During a summer vacation Takuya discovers a strange orb in his father's room, along with a letter containing information about the existence of a parallel world. At first Takuya doesn't take it seriously, but soon he realizes that he possesses a device that allows him to travel to an alternate universe. Is his father alive, after all? If so, where is he? Meetings and conversations with many beautiful girls (including his stepmother Ayumi), as well as a suspenseful investigation await Takuya!

"Yu-No" is a Japanese adventure (still screens viewed from first-person perspective, a lot of dialogue) with a unique feature: multiple paths, which are present in many Japanese bishoujo games, are shown on a special map and can be accessed within the same playing session, by using orbs like the one you found in your home in the beginning. If a path leads you to a dead end, you can use a stone, go back, and investigate another place to lead the story into a different direction. The interaction with the game world is not done through menu commands (except in the prologue), but through point-and-click interface.

"Yu-No" was originally a full-fledged hentai game (it was released for PC-98) with explicit sex scenes. The Saturn version still contains erotic images, but the hentai content was reduced.

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