"That idiot won't be in trainee forever unless he get rid of his act!"
- ―Captain Ohkohchi
- ―Katsuto training himself, Ultraman Zearth 2: Superhuman Big Battle - Light and Shadow
Katsuto Asahi (朝日勝人 Katsuto Asahi) is the protagonist in the film Ultraman Zearth and its sequel. He is the human form of an Ultraman named Zearth, Katsuto hails from the Land of Bright in Nebula Z95.
Asahi is typically dressed in his uniform of a white red striped shirt, grey hat and pants, his Mydo uniform is a red flight suit and helmet.
Coming to Earth to clean the polluted planet Katsuto brought with him an incredible hygiene obsession and a fear of dirt. Joining the Mydo, disguised as a gasoline stand, Katsuto was relegated to the position of janitor because his fear of dirt interfered with his training stopping him from becoming a full-fledged member. However, when the team went out Katsuto would use the time alone to transform into his true identity Ultraman Zearth.
Ultraman Zearth 2: Superhuman Big Battle - Light and Shadow
Pikari Brush/Pikari Brush 2: Katsuto uses this to become Ultraman Zearth. He first activates the brush and starts brushing his teeth. Then he raises it in the air and a flash of light transforms him into his Ultra form.
Ultraman Zearth: Parody Chapter
- Katsuto is seen by some as the most incompetent of all Ultra Hosts. In the first movie he had paralyzing fears of pollution, dirt and anything messy in general, and despite joining Mydo he never graduates from training and was relegated to the role of a janitor while other Ultra hosts have become analyzers and mainly pilots. However by the end of the movies he always works to overcome his fears.
- In the parody chapter, Katsuto's (third attempted) transformation is based on Kamen Norida's transformation, complete with the transformation call "I looooooove the plants! Ultraman. ZEARTH!"