Kokoro Shiina is a supporting character in My First Girlfriend Is a Gal. She is a high school student and a close friend in Yukana Yame's gal group. Kokoro has blonde hair styled in two ponytails tied with red ribbons and gentle droopy eyes, giving her a bright and friendly appearance. Her personality is cheerful and outgoing, and she is known for her kind nature and strong desire to make others happy. Kokoro is deeply loyal, particularly to Yukana, and she is protective of her friends when the situation calls for it. She is determined and acts with genuine goodwill. In the story, Kokoro functions as a supportive friend who provides companionship and occasional advice to Yukana and the other gals. While she is a more minor character in the manga, the anime gives her a somewhat expanded role. Her key relationship is with Yukana, but she also maintains friendly ties with other members of the gal circle. Kokoro does not undergo a significant personal transformation over the course of the series; she remains a steady, amiable presence. She possesses no supernatural or exceptional abilities, relying instead on her social warmth and loyalty.