Kagome Byakudan attends St. Lulim Girls' School on Astraea Hill as a first-year student. She possesses a petite frame, stands short, and has fair skin complemented by sand blonde curly hair, typically arranged in a half braid reaching her upper back. Her eyes appear as dark cyan or green across different sources. Frequently described as doll-like, she is almost inseparable from her teddy bear, Percival, whom she treats as a sentient companion.

Her personality is soft-spoken, shy, and taciturn, often appearing lonely due to few social connections. She primarily communicates through Percival, employing phrases like "Percival thinks..." instead of first-person statements. This habit leads others to underestimate her initially, though some peers sense hidden depth beneath her passive exterior [citation:]. Despite her reserved nature, she demonstrates artistic talent through activities like sand castle building and acting. She also exhibits heightened emotional perception, enabling her to detect distress in others.

Key relationships include her persistent pursuit leading to gradual integration into a friend group with Chikaru Minamoto, Kizuna Hyūga, and Remon Natsume. She harbors admiration for Nagisa Aoi, addressing her as "Nagisa-onee-sama" after Nagisa shared her umbrella during rain. During the cultural festival, she performed as Romeo opposite Tsubomi Okuwaka's Juliet, complimenting Tsubomi as a "beautiful angel with wings".

In the light novel continuity, Kagome experiences significant development when elected as Etoile alongside Makoto Kusanagi. However, she withdraws from the position after Makoto mocks Percival, revealing her steadfast attachment to the bear. Her surname combines "white" (白) and "sandalwood/cedar" (檀), while her given name means "basket woman" (籠女).