Momotarou Densetsu Gaiden ("Peach Boy Legend Side-Story"), known as Momotarou Densetsu Gaiden: Dai 1-Shu ("Peach Boy Legend Side-Story: Volume 1") for PC Engine, is a non-core entry in Hudson's Momotarou Densetsu series of RPGs loosely inspired by the titular folklore figure. It was first released on the Game Boy in 1991, and then ported to the PC Engine the next year and the Famicom the year following that.
The game switches focus from Momotarou to three extra characters, each has their own distinct campaign to play through. One follows a standard RPG route of a hero's journey, another involves the princess of the kingdom of demons as she attempts to uncover an attack on her father's throne with a band of allied monsters, and the third involves a thief who steals money from monsters and gives it to beggars. Each campaign follows the core gameplay of the series: overworld exploration and turn-based combat.