Kazuomi Inui, nicknamed Kazu, is Yuna Ichihara's childhood friend residing in the same apartment building as Yuna and Akari Yamamoto. His surname Inui means "dried, cured," while Kazuomi blends "harmony, peace" and "retainer, subject," symbolizing peace and loyalty. Physically, he has black hair, brown eyes, stands 1.76 meters tall, and weighs 61 kilograms. Born October 6 with blood type B, his personality is carefree and sincere, though Akari Yamamoto perceives him as an airhead due to his straightforwardness.

Akari initially attempts to match him romantically with Yuna, but Yuna clarifies she lacks feelings for him. Kazuomi instead develops mutual affection with Akari. He initially rejects her confession out of respect for Rio Yamamoto's longstanding feelings for her. After confirming Rio's emotional detachment, Kazuomi confesses to Akari, and they begin dating. Their relationship faces challenges when Akari's ex-boyfriend resurfaces and when she relocates to America with her family. Committed to their bond, Kazuomi arranges to move to America, planning to reunite with Akari while pursuing his personal goals.

His friendship with Rio Yamamoto remains pivotal, with Rio's emotional journey directly influencing Kazuomi's timing in pursuing Akari. His childhood connection with Yuna endures platonically despite external romantic pressures.