Kain, sole survivor of his homeworld Feminia after its destruction by Violengiguar's Nine Great Demon Generals, was rescued by Victory Saber and evacuated to the Autobot planet Zone aboard Galaxy Shuttle, accompanied by his winged rabbit-like creature Emusa. Following a Decepticon attack on Zone, Kain fled once more, arriving on Earth where he met the human boy Akira Serikawa. The two developed a close bond, often depicted holding hands or expressing mutual concern in perilous situations, with implications of romantic attraction.

Stationed at the lunar Zone base during Metrotitan's assault, Kain, Akira, and Emusa escaped destruction aboard the Micromaster Rabbicrater. Violengiguar later captured them along with the Autobot Moonradar while stealing the Zodiac energy, holding them hostage within the Galaxy Rocket. The Powered Masters freed them during the battle on the Tenth Planet, where Violengiguar transformed into three insectoid monsters. After Violengiguar's defeat, Kain participated in restoring peace to the Tenth Planet, revitalized with plant life by the Zodiac's energy. Recognizing the need for unity, Kain committed to working alongside Akira, Emusa, and the Transformers to safeguard this newfound peace.

In extended continuity, Kain and Akira resided on Zone years later when Violengiguar's renewed threats emerged. Early concept art depicted Kain with golden hair and a scarf, though this design was revised for his final animated appearance.