Kawasaki is a member of the elite ninth unit of the Sushi Police, serving alongside his colleagues Honda and Suzuki. He is a robot inspector, originating from Tokyo's Ota Ward. As a machine, he is extraordinarily lightweight, and his arsenal is notable for its heavy, explosive power, including rocket launchers, charged particle cannons, and other firearms. However, the extreme recoil from these weapons often sends him flying through the air.

His personality is defined by a cheerful, boisterous, and often mischievous nature. Kawasaki laughs frequently and serves as the comedic core of the group, bringing a sense of playful energy to the team's otherwise rigid mission. He enjoys pranks, such as secretly mixing wasabi into his teammates' tea, and displays a genuine, innocent friendliness even towards adversaries, like the Pasta Police and their robot. Despite being a machine, Kawasaki possesses a depth of thought that sometimes surpasses his human counterparts.

Kawasaki's origins are unique among the unit. He was originally a sushi-making robot manufactured by the Bay Company. His transformation into a Sushi Police officer occurred when Suzuki tampered with his internal systems, replacing his soy sauce fuel with wasabi. This act inadvertently gave him a heart and emotions, effectively granting him consciousness. This background explains his central internal conflict: his programming compels him to destroy incorrect sushi, but his acquired emotions allow him to question the morality and purpose of his orders.

Throughout the story, Kawasaki begins to doubt the methods of the World Food-Culture Conservation Organization. He finds himself agreeing with the arguments of their enemies, the Free Sushi movement, and is horrified when he witnesses the destruction of another robot by Honda, which causes him to question whether his leader possesses any empathy. This internal struggle eventually leads to a rampage where his core programming overrides his consciousness, causing him to attack indiscriminately.

Kawasaki's most significant act comes at the climax of the series. After being recovered and modified, he regains his memories when wasabi is splashed onto him. To save Honda and Suzuki from a rampaging monster, he sacrifices himself by carrying the creature into space, where it collides with a satellite. In his final moment, he displays a peaceful smile before his destruction.