Protagonist of the series, 17 year-old Eiji Shigure is searching for his older sister Ayaka Shigure, after he receives a letter from her. Upon finding information she is last seen in service to billionaire Klein Sandman, Eiji enters Sandman's Saint-Germain Castle to find her, but is unknowingly recruited into the Earthgertz as pilot of the Gran Diva, the G-Attacker. He reluctantly stays with the Earthgertz to assume piloting responsibilities, but above all, will leave once he finds Ayaka in Sandman's castle. In Gravion Zwei, he pilots the Geo Mirage.

Easily angered, Eiji carries a short temper and is annoyed by the carefree and clueless Toga, the other boy in the castle, who has no outside interaction prior to Eiji's arrival, or the feisty Luna, who picks on him for not being more like Toga. Regardless, Eiji is reasonable in his rash decisions and develops a close friendship with the rest of his teammates, knowing firsthand how real the Zeravire threat is, thus willing to see the menacing mechanical beings stopped by helping the Earthgertz in their mission. Voiced by: Kenichi Suzumura (Japanese), Chris Patton (English)