Hii-chan attends Mariya All-Girls Academy as Misuzu's best friend, harboring intense romantic feelings for her. She welcomes Misuzu's physical contact and frequently drifts into vivid daydreams of romantic embraces or dual Misuzus holding her hands. When longing for Misuzu, she interacts with a doll bearing her name, occasionally slipping into hallucinatory states if the real Misuzu holds her hand during these episodes. She assumes Misuzu anticipates watching young girls play in water during summer and expresses unwavering confidence that Misuzu would protect her from any groper.

Hii-chan displays a deep fascination with outer space and cosmic phenomena, rendering her highly susceptible to alien-related stories like those from Naoko-san—who derisively calls her "Vierauge" ("Four-Eyes") due to her glasses. This cosmic enthrallment and credulous nature often trigger her daydreams. Though she escorts Misuzu home for protection against rumored molesters, she exhibits a fearless, unrestrained personality devoid of anxiety.

Within the series' OVAs, Hii-chan investigates a neighborhood groper alongside Misuzu and Naoko-san. The 2012 OVA depicts her fainting under circumstances suggesting possible manipulation by Naoko-san. Her space-related captivation and obsessive fixation on Misuzu consistently define her interactions and minor developments across narratives.