Mario holds a position on the student council at the underworld school, though his specific role is undefined. He exhibits immense physical strength, capable of catching massive boulders barehanded. Protecting Rinne Amagane is his central motivation, driving significant effort to ensure her safety. He mirrors her unwavering determination, persistently fighting opponents like Abel even when faced with certain defeat.

Another character, Who, observes Mario's developing feelings for Rinne and reveals she is the reincarnation of Mario's deceased wife. Mario responds to this revelation with the statement, "Not in this life," indicating his feelings are for Rinne's present self.

In the narrative's second half, Mario receives increased focus, frequently engaging in defiant shouting during confrontations. His narrative function centers on embodying the theme of overcoming self-doubt and acting despite fear. He serves as a catalyst, inspiring others through his example of persistent defiance against overwhelming opposition. While his direct impact on core plot progression is limited—his removal wouldn't substantially alter main events—his confrontations primarily illustrate resistance against forces like Abel, who seeks to demonstrate the futility of opposition. His presence reinforces the thematic exploration of perseverance.