A matchmaking party held in a certain parallel world. In this world, there are no conflicts between races, and peace is maintained quite effectively. Amidst this tranquility, needs such as "I want to meet various races" or "I want to marry someone outside my own species" began to swell. Eventually, these matchmaking parties started being held spontaneously to meet that demand. Participants range from humans, elves, and dwarves to monsters, demi-humans, high-ranking demons, angels, gods, devils, and even evil deities. In short, an incredibly diverse array of species participates.