Hayato operates as the designated pilot for Yumi Francois within the Space Knights, maneuvering the vehicle or support system crucial for her effectiveness as Tekkaman Hiver in combat. Shortly after this assignment, he develops romantic feelings for Yumi. Shyness and a lack of confidence prevent him from openly expressing this affection. David Kruegel, another team member, quickly identifies Hayato's infatuation and regularly teases him about it.

Yumi remains largely oblivious to Hayato's attentions and emotional state. Her focus is predominantly consumed by her admiration for the "White Tekkaman" (Tekkaman Blade). Hayato exhibits intense, passionately angry emotional reactions when he perceives threats to his relationship with Yumi or dangers to her safety. Despite these outbursts, he demonstrates absolute loyalty to Yumi and the Space Knights during missions. His story arc centers on his unrequited feelings for Yumi and his interactions within the team dynamic, concluding without resolution to his romantic subplot.