During their youth, Nino Arisugawa and Momo Sakaki vowed to use their music to reunite if ever separated. When Momo abruptly leaves, Nino, consumed by an unspoken sorrow, adopts a mask. Encountering the music composer Yuzu, who dubs her 'Alice,' Nino finds solace in his melodies while unknowingly captivating his heart. Their weekly beach rendezvous halts suddenly, only to resume six years later in high school, where Momo also enrolls. Driven by her promise to Momo, Nino sings Yuzu's compositions in hopes of bridging the gap, unaware of the intricate love triangle emerging as Yuzu yearns for her amidst the echoes of their intertwined pasts.