Hamanaka Midori is a third-year student at Sakuragaoka High School. He possesses a relatively tall stature, messy short hair, and consistently wears a bandage on his cheek. A small snaggle tooth on his mouth's right side and a pierced left ear are notable features. His school attire includes his dress shirt unbuttoned at the top, revealing a green undershirt, with sleeves rolled up to his elbows; he often ties his blazer around his waist. Outside school, he favors large, clunky brown boots.

Personality-wise, Midori appears energetic and boisterous socially yet becomes anxious, shy, and delicate in romantic contexts. He acknowledges his romantic insecurities and actively strives to become "cooler" and "manlier" to support his loved one. This contrast between outward confidence and inner vulnerability shapes his interactions.

His primary passion is music, specifically playing guitar in the school's music club. After graduation, he pursues a musical career, writing original songs and performing as both guitarist and lead singer in a small-time band.

Midori's most significant relationship is with Sena Narumi; they share mutual romantic feelings. Initially, neither confessed, instead observing each other during train commutes. Their first meaningful interaction occurred when Sena lent him an umbrella in the rain. He returned it the following Monday, exchanged phone numbers with her, progressed to spending weekends together, and they began dating. Within this relationship, he is the more passive partner despite his wholehearted support for Sena. His close friendship with Haruki Serizawa dates back to middle school, characterized by Haruki's playful teasing. Midori also interacts with Mona Narumi, Sena's younger sister, who initially disapproved, feeling he didn't live up to Sena's praise. Mona ultimately accepted the relationship due to Sena's happiness.

Background details include his Kansai dialect, indicating origins in that region before moving to Tokyo. He shares characteristics such as height, birthday, and musical interests with the singer Gero, who inspired him. Academically, he performed poorly before high school and barely qualified for Sakuragaoka admission, as noted by Haruki. His name carries symbolic meaning: "Midori" translates to "green" or "kingfisher," while his surname "Hamanaka" combines "seacoast" or "river bank" (濱) with "center" or "inside" (中). He is one of the few characters without a solo song outside the main or other storylines.