Peggy Hayase, originally named Nami Hayase in Japanese, starts as the protagonist's primary rival before developing into a close friend and ally. As captain and star player of Hikawa Junior High's girls' volleyball team, she exudes cold arrogance, particularly toward new teammates like the protagonist. Her leadership style and perceived superiority cement her as an Alpha Bitch figure, alienating all but a small loyal faction. A crushing defeat and mass desertion by teammates trigger her Heel–Face Turn, prompting self-awareness and respectful treatment of others. Her rivalry with the protagonist evolves into Fire-Forged Friends, marked by enduring mutual loyalty even when they join opposing professional teams.

Hayase demonstrates exceptional volleyball expertise as a high-level receiver and server. Though not the absolute top player like the protagonist or Eri Takigawa, her technical precision and analytical approach establish her among the best in her position. Her methodical Technician playing style starkly contrasts the protagonist's instinct-driven Performer method. Post-junior high, she joins a professional team under strict coach Daimon, becoming a key athlete. Despite her skill, Daimon sidelines her for newer talents like Hikaru, fueling ongoing professional tensions.

Visually, she sports blue hair and a calm, serious demeanor, opposing the protagonist's red hair and energetic presence. This contrast extends to their team colors—blue versus red. Early narrative threads position her as a Romantic False Lead for Sho Takiki, igniting a Love Triangle with the protagonist. Initially dismissive of admirers, she discards unread love letters, though this subplot fades as the series advances.

In the 2008 China-set sequel *New Attacker You!*, Hayase reappears with diminished focus. She contacts the protagonist to aid the struggling Dragon Ladies team, but her role remains secondary to new characters and plotlines. The sequel maintains her established persona without significant evolution or backstory expansion.