Wataru Komatsuzaki is Lan Komatsuzaki's younger brother, residing with her under their guardian Jin Kiryu. He studies as a first-year at Seiryō Academy. A life-threatening injury occurred when Sonnet Barge caused an F-1 race crash, scattering debris that critically wounded him; Lan saved him through an emergency blood transfusion.

Afterward, Wataru theorizes he may have gained latent esper abilities from Lan’s blood. He carries guilt over Lan’s injuries and subsequent hardships, frequently aiding her and voicing anxiety for her safety.

Wataru idolizes Shūichi "Bird" Torigai as a role model. He allies with Bird during pivotal incidents—exposing a fraudulent police operation targeting Lan and storming the Talon organization’s fortress to rescue her. These efforts showcase his protective loyalty to his sister and resolve to combat threats with comrades.