Iroha Kohinata is a first-year high school student defined by contrasting personas. At school, she embodies a bright, kind, and beautiful honor student who maintains politeness toward everyone, recognized for her academic excellence and well-dressed appearance. Outside school, particularly around Akiteru Ōboshi, she displays excitable, clingy, and teasing behaviors, frequently invading his apartment uninvited to demand attention—actions that consistently irritate him. These antics stem from her romantic feelings, though she reveals seriousness during critical moments, such as supporting Akiteru through Alliance game development conflicts by urging him to confront his struggles.

Physically, Iroha possesses bright golden hair noted for its fluffiness, often likened to an emperor penguin when combined with the headphones she drapes around her neck. Her typical attire is a short-sleeved uniform and skirt, accentuating her long, slender legs. She avoids accessories or embellishments that might associate her with subcultures, reinforcing her archetypal high school girl image. A key background element is her clandestine pursuit of voice acting—a career opposed by her family—where she anonymously contributes voice work to the Alliance's projects.

Her relationships drive significant development arcs. With Akiteru, her persistent annoyance masks deeper affection, yet she respects boundaries during his emotional crises, shifting from playful interference to authentic support. Her dynamic with Mashiro Tsukinomori evolves from rivalry—sparked when Iroha discovers Mashiro's confession to Akiteru—into nuanced camaraderie. Though fearing romantic competition could fracture their friendship, Iroha protects Mashiro from bullies during a mall confrontation, demonstrating fierce loyalty. This coexists with lingering jealousy, exemplified when she sends Akiteru a bikini photo to "outdo" Mashiro. Her surname "Kohinata" translates to "small sunny place," while her given name "Iroha" blends "color" (彩) and "feather" (羽).