Kisonosuke is Noel's faithful dog companion, consistently appearing beside her. Referred to as "Pup" in English, they share a home on a celestial body, relaxing together under the sun before their journey begins. When Noel embarks on her interstellar mission to deliver ice cream to the sun, Kisonosuke joins her aboard the aircraft.

During the voyage, Kisonosuke observes phenomena like a blinking light that becomes a planet, prompting a landing where they meet inhabitants. On Planet Gaudy, Kisonosuke remains present but passive as Noel influences citizens to remove garments. The character serves a narrative function by reminding Noel of their primary objective, directly prompting their departure to continue toward the sun.

After delivering the ice cream and receiving the sun's warning about encroaching smog, Kisonosuke accompanies Noel to locate the pollution's source. When smog envelops their aircraft, Kisonosuke escapes underwater with Noel to a submerged planet. Throughout the underwater exploration, Kisonosuke accompanies Noel, observing marine environments, witnessing environmental degradation like ailing sea creatures and seabed sludge. The character remains present during subsequent musical interludes, pollution battles involving the superpowered whale Super Zoomer, and the concluding environmental remediation sequences. Kisonosuke appears in all described journey phases without documented dialogue, personality traits, backstory, or character development.