Arimi Suzuki is a pivotal secondary character who first appears as a former classmate of Yuu Matsuura from his previous school, Sakaki Gakuen. Before the events of the story, Arimi convinced Yuu to enter a three-month trial relationship where she attempted to make him fall in love with her. At the end of this period, however, Yuu still regarded her only as a friend, leaving her feelings unresolved.

Arimi is depicted as a fashionable, well-groomed, and popular young woman who carries herself with refinement and poise. Beneath her sophisticated exterior lies a deeply sincere and romantic nature; she does not treat matters of the heart lightly and is very direct about what she wants. Her frustration with Miki Koishikawa stems from what she perceives as Miki indecisiveness, as Arimi believes Yuu deserves someone who can commit fully rather than someone torn between two people.

Arimi primary motivation throughout much of the story is her enduring love for Yuu. Upon re-encountering him at a theme park while he is with Miki, Arimi realizes she still harbors strong feelings for him and begins frequenting places he visits, including his high school and his part-time job. Her determination leads her to form an alliance with Ginta Suou, Miki childhood friend and another spurned suitor, in an attempt to drive Yuu and Miki apart through a scheme designed to provoke jealousy. However, Arimi possesses enough emotional intelligence to recognize when she cannot win. Observing how Yuu behaves around Miki, she comes to understand that his feelings for Miki are genuine, and she ultimately ceases her pursuit of him.

Arimi role in the story serves as a catalyst for relationship drama and as a rival who tests the strength of the main couple bond. She is also notable for her athletic ability, being one of the strongest members of the track and field club at her school. Her key relationships extend beyond Yuu. Her partnership with Ginta, initially a tactical arrangement, deepens over time. As she stops chasing Yuu, Arimi develops real feelings for Ginta, and the two eventually become a couple. This development is complicated by the presence of Tsutomu Rokutanda, Ginta cousin, who harbors an unrequited love for Arimi that he struggles to let go of until late in the story.

Over the course of the narrative, Arimi undergoes significant development. She transforms from a determined rival attempting to reclaim an old love into someone who accepts rejection gracefully and finds a new, genuine connection with Ginta. Her arc represents a mature acceptance that love cannot be forced and that happiness can arise from unexpected partnerships. Some viewers have found her to be one of the most compelling characters in the series precisely because she knows what she wants and pursues it with honesty and energy, in contrast to the more hesitant protagonists.