Midori Ōmama attends class 1-Q alongside classmates Mio Naganohara, Yuuko Aioi, Mai Minakami, and Nano Shinonome. Frequently seen in scenarios involving Mio, she engages sporadically with peers, her demeanor characterized by a willful and selfish streak—traits explicitly confirmed by manga creator Keiichi Arawi during fan interactions.

Her name emerged from a fan-proposed fusion of "Midori" and the former town "Ōmama," later incorporated into Midori City during a 2006 municipal merger, weaving a lighthearted nod to real-world locales. Midori debuted in *Nichijou Episode 0*, an original video animation preceding the main anime series.

Available records outline no specific background, developmental arcs, or appearances in spin-offs or films beyond her episodic school-based cameos. Her documented presence remains confined to fleeting classroom exchanges, with existing sources offering no expanded narrative or character progression.