OVA
Description
Mitsuki Hayase emerges as a central figure whose story unfolds across multiple installments. A top competitive swimmer in high school with national potential, she earned admiration from peers like Akane Suzumiya. Mitsuki actively facilitated the relationship between her best friend Haruka Suzumiya and Takayuki Narumi, all while concealing her own feelings for Takayuki. On her birthday, she intercepted Takayuki as he traveled to meet Haruka, requesting a silver ring as a gift. This delay contributed to Takayuki arriving late for the date, coinciding with Haruka suffering a critical accident.

Consumed by guilt following Haruka's coma, Mitsuki experienced a decline in her swimming performance and ultimately abandoned her promising career. She devoted herself entirely to caring for the psychologically shattered Takayuki. To support them financially, she secured employment at Hanezawa Trading Company. During this period, she initiated a physical relationship with Takayuki, symbolically severing her signature ponytail afterward. Their intimacy was discovered by Akane Suzumiya, who witnessed Mitsuki in Takayuki's bed, fostering Akane's enduring hostility.

Over the next three years, Mitsuki and Takayuki built a stable partnership. His emotional and professional recovery is attributed to her unwavering support. This stability fractured dramatically upon Haruka's awakening. Mitsuki confronted intense jealousy as Takayuki resumed visiting Haruka, culminating in a drunken demand that he cease all contact. Her emotional turmoil escalated when former swimming rivals nearly exploited her intoxicated state; Shinji Taira intervened, leading to an impulsive encounter between them. After nursing Takayuki through illness, she concluded their relationship, returning the silver ring and moving out.

Her attempt to explain the situation to Haruka resulted in being slapped and rejected. The primary narrative resolves on a symbolic hilltop where Takayuki, having resolved his feelings for Haruka, reaffirmed his bond with Mitsuki. She was later seen emotionally responding to Akane's swimming achievement. Her name, reflecting water ("mi") and moon ("tsuki") elements, aligns with her narrative associations.