Yuki Kohinata is the eldest of the three Kohinata sisters, residing above Miu and Nana in the family hierarchy. She lives with her sisters, her mother Yukie Kohinata, and her stepbrother Akira Kohinata after their parents' remarriage. Her biological father, an archaeologist, remains absent pursuing professional commitments post-honeymoon.

Yuki possesses brown eyes and long red hair reaching her waist, typically adorned with ribbons. She stands 151 cm (approximately 4'11½") tall with measurements of B77 cm (~30"), W55 cm (~21½"), and H79 cm (~31"). Depicted as a teenage girl, she is often seen wearing a dress.

Her personality is gentle, cheerful, and generally well-mannered, though marked by a clumsy streak. She maintains an active life as a member of her school's tennis team, where she befriends teammate Azusa Sutō.

Her narrative role centers on her relationship with Akira. After Akira is discovered in a compromising situation with Yukie, he becomes bound by a supernatural contract compelling him to collect the "love juices" of Yuki and her sisters within a set timeframe. Using bottles provided by the goddess Inana, Akira must target Yuki under threat of dire consequences to fulfill this obligation.