Personality contrasts define him: level-headed and cool compared to Wataru's excitability, yet exhibiting a standoffish demeanor that favors solitude. He routinely rejects assistance from others and possesses a short temper, often losing composure to lash out at companions. This reluctance for group engagement extends to avoiding dance sequences during credit rollouts, though he sporadically participates in brief moments.

Within the OVA *Mashin Hero Wataru: The Neverending Story*, Umihiko reunites with Wataru and allies against a demon-world threat. The narrative adopts a darker, introspective tone centered on a mortal quest devoid of mecha support. Here, he witnesses Mount Soukai's partial destruction and aids in sealing the malevolent entity Enraoh, maintaining his role as a consistent core group member.

His presence spans multiple franchise installments, adhering to established traits without significant deviation or expanded backstory. Later media, including anniversary projects, continue his inclusion, preserving this consistency.