Ku-chan, a goddess of sexual love, assists Natsu Andou, a 30-year-old virgin librarian, in overcoming her romantic and sexual inexperience. As Pi-chan's twin sister, she typically operates supportively from the background, often silent or observing rather than taking direct initiative. Her appearance features pink hair, orange eyes, and consistent Gothic Lolita attire.

A defining communication limitation involves her frequent "forgetting" of proper Japanese, leading to unintelligible sounds or incorrect languages that require her sister's interpretation. This contributes to her perception as less engaged, though she occasionally demonstrates unexpected effectiveness when acting alone. Her behavior includes consuming unusual substances like mustard, honey, and Tabasco sauce. Consuming these spicy foods triggers a temporary transformation, granting her heightened confidence, directness, and fluent Japanese speech. In this state, she exhibits greater competence in romantic guidance than Pi-chan and asserts strong protective instincts over those she cares about.

Her relationships reveal deeper dimensions: she harbors romantic feelings for Macaron, the cross-dressing younger brother of fellow deity Daigorou, and actively shields him from teasing or discomfort. This protective tendency manifests physically when she intervenes after Macaron faces mockery about his gender expression. Despite her usual reticence, she demonstrates genuine investment in Natsu's emotional well-being and desires her eventual happiness with protagonist Hayao Imagawa. Moments of maturity and assertiveness during her empowered states contrast with her typical background role, highlighting her capacity for growth.