Mikoto Kondō attends Seitetsu Gakuin High School and is Natsuru Senō's childhood friend. Her archaeologist father's frequent international travel forced her to defer school and live abroad, forging an adventurous, risk-taking personality. These long absences from Natsuru were punctuated only by postcard communication. After returning, she boldly reconnected with him, exhibiting an uninhibited nature that included cleaning his house wearing nothing but an apron. Her time overseas also ignited a fierce passion for curry; she cooks it constantly, aggressively defends it from criticism, and serves it to Natsuru despite his aversion.

She harbors unspoken romantic feelings for Natsuru, masked by pride. These feelings manifest as jealousy towards other girls close to him, especially upon hearing rumors of a female Natsuru (his Kämpfer form) and witnessing advances from Akane Mishima and Shizuku Sangō. Insecurity about competing for his affection fuels her rivalry. During the Miss Seitetsu contest, she caught a bouquet thrown by Kaede Sakura containing a hidden Messenger—the Entrails Animal plush Strangled Stray Dog—transforming her into a Red Kämpfer, specifically a Schwert-type wielding a katana.

Her Kämpfer transformation is drastic: light brown hair turns completely white, longer, and unrulier; facial features become more angular; eyes appear sharper. Her school uniform inverts its color scheme, with black replacing white and vice versa, and sleeves shorten. The extent of these changes means she rarely worries about recognition, though Natsuru identified her immediately due to their closeness. In battle, she favors aggressive, head-on tactics over strategy, using her katana for powerful slashes rather than finesse. This impulsiveness often leaves her open to flanking or environmental hazards.

Initially a Red Kämpfer opposing the Blue faction, including Natsuru's female form whom she sought to eliminate, she felt profoundly betrayed upon discovering the female Kämpfer was Natsuru himself, believing he withheld the truth due to distrust. This caused anger and estrangement. She later defected from the Red Kämpfer after learning Shizuku had also abandoned them, joining Natsuru and Akane. Unlike other Kämpfer, she displays genuine enthusiasm for the battles, treating them as an exciting game with little remorse for defeated opponents. Her emotional impulsiveness extends beyond combat; she struggles to keep secrets, promptly revealing the Kämpfers' existence, and often prioritizes personal desires over group interests.

In later events, including the OVAs *Kämpfer für die Liebe*, she collaborates with Shizuku to investigate the Moderators, primarily for camaraderie rather than ideological opposition. She remains part of the coalition with Natsuru, Akane, and Shizuku. Her romantic rivalry persists, leading to open competition for Natsuru's attention. Despite her feelings, she ultimately maintains a childhood-friend relationship without progressing to romance.