Takaya Aiba, known as D-Boy, is the central figure of the original *Tekkaman Blade* series whose story extends into the sequel OVA *Tekkaman Blade II*. His ordeal began when the alien Radam captured his family during a space mission. Rescued by his father before the Radam's brainwashing completed, Takaya became Tekkaman Blade to fight the Radam and his transformed family members. This conflict climaxed in his victory over the Radam leader, his brother Kengo (Tekkaman Omega), a battle that inflicted severe physical and mental deterioration. The original series concluded with Takaya amnesiac, confined to a wheelchair, and dependent on caretakers due to the cumulative damage from his transformations and the final fight.

A decade later in *Tekkaman Blade II*, Takaya shows partial recovery. He regains limited mobility and speech but remains largely detached, his memories of the past fragmented or absent. He lives under the care of Aki Kisaragi, now leading the rebuilt Space Knights organization. His role shifts from frontline warrior to a symbolic presence and occasional combatant. New characters, like Yumi Francois, revere him as a legend inspired by his past heroism. Despite his disabilities, he participates intermittently in battles, notably confronting the antagonist Dead End (Tekkaman Dead). During their final clash, he sustains critical injuries, highlighting his fragile condition. His relationship with Aki deepens into a romantic partnership, and he assists in mentoring the new generation of Tekkamen, though his involvement remains constrained by his health.

Takaya's character arc across both series explores sacrifice and resilience. The original series depicts his profound physical and emotional decline from repeated transformations and familial conflict. The sequel emphasizes his adaptation to disability and his transition into a mentorship role. His enduring legacy resonates within the new Space Knights team, though his direct impact in *Tekkaman Blade II* is secondary to the new protagonists.