Mieko Yotsuba emerges as a striking red-haired woman navigating entrance exams for Keio University. Her successful admission contrasts sharply with protagonist Touma Inaba's failure; he fabricates acceptance to win her affection, forging their initial connection on this foundation of deceit.

She harbors a significant secret: a betrothal to a man residing in Europe. This arranged engagement constantly complicates her deepening bond with Touma and steers her choices. Despite actively seeking shared memories with Touma and showing clear interest, her commitment to the distant engagement remains an ever-present factor.

Manipulation by rival Tatsuhiko Mashu exposes Touma's lie, prompting Mieko to sever their relationship and briefly accept Mashu. Suspicions of Mashu's infidelity later drive her to rekindle a physical connection with Touma at a love hotel.

Her journey culminates in a final encounter with Touma preceding her marriage. They share another intimate moment, concluding their tumultuous romantic entanglement after prior conflicts and reconciliations.