Matsuo, a spirited orphan at Blue Sky Orphanage, thrives within its core group, bonding with peers through American football under Takeshi’s guidance. A rain-soaked game sparks a pivotal moment: his well-meaning plea for Takeshi to seek happiness inadvertently drives his mentor to flee, triggering a cascade of events. A mysterious crystal pierces Takeshi’s chest, unleashing a radiant surge that catapults Matsuo and allies onto an otherworldly vessel.

Aboard the UFO, Matsuo uncovers Takeshi’s alien lineage and the looming peril of General Dazaan’s forces. Stepping into the role of pilot for the Header robot—one-third of the combinable mecha alongside Trangur and Legger—he pledges to defend Earth, maneuvering support craft in battle to aid their collective stand.

Though the youngest and most impulsive of the team, Matsuo’s defiant streak clashes with authority yet fuels his relentless courage. He fearlessly challenges opponents regardless of size or status, driven by an unwavering moral compass. His bond with Takeshi blends fierce loyalty and sibling-like reverence, anchoring his growth amid chaos.

Clad in a vibrant yellow football jersey mirroring his team’s color-coded unity, Matsuo embodies both the recklessness and resilience of youth, his journey etched into the primary saga’s chronicles without extension into spin-offs or sequels.