Miyako Ookura is the protagonist's childhood friend and neighbor. She possesses a cheerful, straightforward, and impatient personality. Miyako actively supports the protagonist by waking him up, delivering his monthly allowance, and providing information about other girls attending Kirameki High School. She constantly carries a bunny doll crafted together with the protagonist during their childhood.

Initially fulfilling a non-romantic, supportive role, Miyako becomes datable only after repeated invitations from the protagonist. Entering a relationship triggers significant psychological changes; misunderstandings about the protagonist's feelings lead her to develop psychosis. Her personality shifts dramatically towards quietness, she adopts darker clothing, and engages in ominous dialogue. Miyako ceases providing information or allowances and intensifies stalking behaviors, closely monitoring the protagonist's interactions with other girls.

This psychological state manifests gameplay consequences: if the protagonist dates others during this phase, he confronts the bunny doll's malevolent spirit. Continuing to date Miyako eventually restores her original personality, though she permanently stops sharing information about other girls. The bunny doll may still intermittently disrupt attempts to pursue other relationships.

Miyako enjoys cooking and sewing and has a noted fear of heights. Her height is 165 cm. Her given name combines "miya" (都, metropolis/capital) and "ko" (子, child), while her surname "Okura" (大倉) means "big warehouse" or "storehouse". She maintains a close friendship with Itsuki Maeda.

In non-violent antagonistic interactions, Miyako utilizes "Tokimeki Bombs" to spread rumors about the protagonist, leveraging her deep knowledge of him to maximize emotional damage. During her unstable phase, she gains a "Heartbreak Increase" skill to amplify these effects while remaining immune to similar tactics from others.