Chinatsu Morikawa faces significant family financial hardship after her father's company bankrupts, forcing them to sell their home and relocate to an old apartment. She insists on continuing studies at a private prep school despite parental concerns, funding tuition through part-time jobs.

Her childhood centers on a deep friendship with Suzuko Homura, including a promise to remain friends forever. This bond profoundly influences Chinatsu, though she later develops jealousy toward Suzuko's effortless sociability and creativity. Resentment festers as Chinatsu feels pressured to uphold Suzuko's idealized image of her, fueling internal conflict.

Becoming a Selector in memory-wagering battles, early losses deplete her memory-storing coins. Combined with mounting pressures, this triggers a personality shift into cold manipulation. She joins Kou Satomi's network as a recruiter, coercing other Selectors through flattery and threats. Her battle style turns sadistic, and she openly hates Suzuko and Ril (Suzuko's LRIG), blaming them for emotional constraints.

Chinatsu intensifies efforts to erase Suzuko-related memories, viewing them as chains. She rejects Shohei Shirai's romantic advances, manipulating him into a traumatic battle to deepen her isolation. Mental deterioration peaks in a breakdown where she questions her villainous perception. Witnessing Yukime—a LRIG who overtook her Selector—suicide after lamenting human suffering, alongside Kiyoi Mizushima's warnings of the battles' darkness, forces Chinatsu to reconsider her path.

Surviving the battle time limit costs most memories, including those of Suzuko, reverting Chinatsu to her shy childhood self. Suzuko, retaining her memories, patiently rebuilds their friendship. Through this reconnection, Chinatsu gradually regains her open demeanor, with the journey highlighting memory and identity's fragility.