Mariachi resides in the fictional Mexican town of Madakueruyobaka and is defined by an ardent passion for singing and guitar playing, frequently seen performing music.

When aggressive, sound-sensitive cacti attack the town, Mariachi joins a small band of survivors that includes the visiting Nohara family. The character aids in the group's survival efforts, with a specific musical talent becoming strategically vital as the destructive cacti are drawn to noise.

Mariachi helps formulate a plan to lure the cacti away from town using a vehicle called the "Cactus Car," capitalizing on the plants' attraction to sound. This plan is thwarted when the town's sole bridge exit is destroyed in an accident.