Oharu is a 16-year-old girl with ankle-length purple hair and matching violet eyes, typically clad in a pink kimono. She co-manages the Four Seasons tea house near the Mushibugyo office. Orphaned by giant insects, she lives with her grandfather and holds a fatalistic perspective on humanity's conflict with the creatures, initially shaping her shy and reserved nature. Despite this, she demonstrates consistent kindness and hospitality in her work.

Her outlook shifts when Jinbei Tsukishima rescues her from the Roof Prison Spider, sparking deep affection for him. In his presence, she frequently blushes, becomes flustered, and stumbles or falls, leading to recurring accidental physical contact that provides lighthearted moments. These incidents contrast her otherwise proper and traditional demeanor.

Gradually, her one-sided admiration for Jinbei evolves into mutual respect. She supports his efforts against insect threats while maintaining her tea house duties, embodying the Yamato Nadeshiko archetype through grace and domestic skill. Underlying persistence and emotional resilience emerge, moving beyond her earlier passivity.

By the series' conclusion, she marries Jinbei as one of his three wives, alongside Hibachi and Kuroageha, and bears three children. This marriage establishes her within a stable, familial structure, completing her journey from trauma-induced insecurity to fulfillment.