Bunbuu hatched from a mysterious egg found in an automobile factory junkyard, revealing a sentient vehicle form. This character sports a distinctive yellow body blending vehicular and creature-like traits and exhibits an innocent, playful personality. Bunbuu communicates verbally through speech, interacting with human companions.

After a rescue from potential destruction at the junkyard, Bunbuu forms an immediate bond with a young human named Ken. A primary motivation drives Bunbuu's narrative: a global search for an absent maternal figure. This quest leads to extensive travel across diverse environments. During the journey, encounters with other talking vehicles often spark races; floral scents temporarily boost Bunbuu's speed and strength to overcome challenges.

Bunbuu constantly evades a persistent pursuer seeking capture for undisclosed purposes. Various episodic challenges arise during travels, including perilous encounters with wildlife like piranhas, gorillas, and polar bears. Bunbuu resolves these through floral power boosts or compassionate resolutions recognizing misunderstood creatures. Character development shows through growing empathy, demonstrated by assisting others—such as transporting expectant mothers or reuniting animal offspring with parents.

Maturation occurs as Bunbuu overcomes fears during environmental challenges like underwater exploration or quicksand hazards. The narrative concludes upon successfully locating the maternal figure, resolving the core journey motivation. Throughout the progression, Bunbuu consistently serves as both a dependable companion and a determined seeker of familial connection.