Yae Yamabuki, affectionately nicknamed "Yae-chin," shares a long-standing close friendship with Tsubomi Tachibana, her fifth-grade classmate for many years. She possesses a tall, slim physique and exhibits a generally calm, reserved demeanor. While often displaying greater maturity and composure than her peers, Yae harbors significant self-consciousness about her physical development during puberty, specifically concerning her flat chest and the experience of buying her first bra.

Privately, Yae holds romantic feelings for Yō Saegusa, a quiet and popular classmate considered the "class idol." Their mutual affection blossoms into an official relationship in chapter 5 of the source material. To avoid provoking jealousy among Yō's admirers, they maintain discretion about their dating status. A notable milestone occurs in chapter 9 when they share their first kiss.

Her friendships, especially with Tsubomi and Rea Katō ("Rea-Pi"), form a central pillar of her character. Within this trusted circle, Yae is open and willing to discuss personal concerns. She demonstrates notably less susceptibility to embarrassment than Rea, though her emotional maturity coexists with persistent insecurities about her rate of physical maturation relative to her peers.