Akari Kaga is of mixed Russian-Japanese heritage, with striking blue eyes and short, messy blonde hair often secured with a hairpin. Originally a short-tempered tomboy, her personality transformed after moving to Hiroshima eight years before the main events, evolving into a cheerful and outgoing demeanor. She frequently masks her true feelings behind humor and teasing, while remaining fiercely loyal and protective of her close friends. Her deep bond with childhood friends Haruto Kirishima and Takashi Yura, formed when they defended her from bullies, gives her an intuitive understanding of their emotions and an ability to detect dishonesty. Despite her generally carefree and disorganized nature, she is comfortable enough to change clothes in their presence and often reacts strongly to Takashi’s perverted tendencies.

In high school, she joins the tennis club and befriends transfer student Yuzuki Eba. She harbors a crush on Narumi Kanzaki and orchestrates a double-date camping trip involving him, Yuzuki, and Haruto, only to discover that Narumi’s feelings lie elsewhere. She recovers quickly and resumes teasing her friends about their romantic lives. When Haruto decides to move to Tokyo to pursue Yuzuki, Akari fiercely opposes his choice in a heated argument. At a farewell gathering at her home, she kisses Haruto on the lips, implying latent romantic feelings. Later attending university in Tokyo alongside Haruto and others, she confronts him about insensitive behavior toward his girlfriend Asuka Mishima. When Haruto later leaves Asuka to be with Yuzuki, Akari joins the friend group in rejecting him, declaring an end to their friendship, though she eventually reconciles with both Haruto and Yuzuki.

After learning of her father’s collapse, Akari drops out of university and returns to Hiroshima to work. Before departing Tokyo, she shares a private conversation with Haruto on her porch and gives him a French kiss, framing it as a symbolic promise to marry him should his relationship with Yuzuki fail. Despite this gesture, she ultimately marries Narumi Kanzaki, becoming Akari Kanzaki, while retaining lingering affection for Haruto. Her journey reflects a transition from adolescence to adulthood amidst evolving personal relationships.