Ibuki Yagami serves as class representative at the high school where Yusaku Godai works as a student teacher. She initially aids his adjustment to the all-girls environment until witnessing him cry, which she misinterprets as grief over a past girlfriend. This sparks her intense romantic obsession. She pursues Godai relentlessly, sparking school rumors that frustrate her by diminishing her genuine emotions. Her bold advances culminate in locking them inside a gym storage closet and partially undressing to coerce intimacy, resulting in Godai's discovery by the principal and Kyoko Otonashi in a compromising state.

Upon learning of Godai's affection for Kyoko, Ibuki declares Kyoko her rival, dismissing her as an unworthy coward clinging to her late husband. Her tactics escalate in aggression, driven by the conviction that only she understands and deserves Godai. She infiltrates his personal life at Maison Ikkoku after he misses a vital job interview, confronting him and locking herself inside his Room 5. She abandons school attendance, relying on friends for financial support during her self-imposed confinement to pressure her father into hiring Godai at Mitsutomo.

Her father intervenes to negotiateserves, prompting Godai’s explicit rejection and affirmation of love for Kyoko. Ibuki’s continued presence causes further chaos, including a kitchen mishap filling the room with smoke. Her father ultimately provides Godai a job recommendation to resolve the standoff, though the position later collapses with the company. Ibuki departs Maison Ikkoku only after Godai’s angry demands, maintaining until the end that he secured the opportunity solely through her influence.