Ichiko Ono is Yumemi Hidaka's classmate and childhood friend. She possesses a positive, energetic personality and consistently encourages Yumemi during gloom. Ichiko exhibits strong protective instincts toward Yumemi, rooted in her own insecurities and co-dependent tendencies, which can manifest as overly controlling behavior.

During childhood, Ichiko quietly wished to see the floating islands Yumemi described. However, an outburst from Ichiko directly led to Yumemi adopting the habit of carrying a pink umbrella to block her view of the sky. Following the events of the first OVA, Ichiko becomes anxious whenever Yumemi gazes skyward, fearing the "red man" might take Yumemi away to a place beyond her protection. She frequently tries to convince Yumemi that Munto and the celestial islands belong to a realm where they do not belong.

Within the school environment, Ichiko is popular and athletic, contrasting with friends Yumemi and Suzume, who are sometimes considered "space-cadet" and "childish" respectively. Classmate Takashi Tobe admires her, though Ichiko remains unaware of his feelings. Suzume later reassures Ichiko about Yumemi's safety when Yumemi decides to help Munto in the second OVA. During this period, Ichiko, Yumemi, and Suzume work part-time at Takashi's family shrine.

Her protective nature evolves into a central conflict as she struggles to balance her desire to shield Yumemi with allowing her friend's autonomy, particularly concerning Yumemi's connection to the heavenly world. This struggle underscores her loyalty's complexity and underlying emotional vulnerabilities.