Wooser is a yellow, bunny-like alien creature of unknown species, possessing black eyes and a central facial dot identified as a nose. He arrived on Earth from an alternate planet, discovering infant twins Rin and Len after an accident killed their parents and destroyed their home. Assuming responsibility for raising them, he constructed a robotic aide named Darth Wooser for their care and protection.

Despite his cute appearance, Wooser exhibits a selfish, lazy, and crass personality, with fixations on meat, money, and girls—particularly those in school uniforms. He lives a NEET lifestyle, often freeloading at the twins' home, though occasional hints suggest he works as a manga artist.

Following an awakening after a tragedy, he became confused and plotted to assassinate and replace a general resembling him to remake history. He later defended Earth from an alien armada, becoming stranded in space. During this ordeal, he encountered Ultraman Zero and the Ultimate Force Zero; they encouraged him and facilitated his return to Earth.

Wooser also appears in crossover media, including a cameo as a restaurant customer in *Kaiju Sakaba Kanpai!* and as a plush toy in *SSSS.GRIDMAN*. His relationships center on Rin and Len, whom he continues to live with, and Darth Wooser, his self-created robotic aide.