Chiharu Okiyama is a supporting character who appears in the ninth episode of the anime. She is introduced as the twin sister of Koharu Okiyama, a lifeguard the main characters encounter during their trip.

Chiharu is portrayed as a calm and understanding presence, particularly in contrast to her sister. While Koharu is initially hostile and resentful towards the visiting girls due to her fear of change, Chiharu offers a more mature and empathetic perspective. She is aware of the emotional pain her sister is going through, which stems from the departure of a beloved local doctor who is being replaced. Rather than dismissing Koharu’s feelings, Chiharu provides support and a moment of clarity. In a key scene at the doctor’s former office, she reassures Koharu that she is not the only person who misses him, helping her sister to confront her grief and begin to let go of her selfish wish for things to stay the same.

Chiharu’s role in the story is directly tied to the emotional resolution of her sister’s conflict. She acts as a catalyst for Koharu’s development, enabling her to accept the upcoming changes, including the arrival of a new doctor. By guiding her sister through her bottled-up feelings, Chiharu demonstrates a deep bond of familial care and emotional intelligence. Her actions indirectly affect the main protagonist, Saki, whose own struggle with the idea of moving to the same town reaches a turning point as she witnesses this acceptance. Chiharu does not possess any supernatural abilities herself, but her introduction occurs as the main characters are using the local wishing rock, and her personal drama unfolds alongside the magical events of the episode.