Yukie Kohinata, mother to Yuki, Nana, and Miu, became stepmother to Akira Kohinata after remarrying an archaeologist, integrating him into their family. She possesses striking red eyes and hip-length hair typically shown as pink or red, often styled with a ribbon in a ponytail. Her adult appearance includes a height of 5'4" and measurements of 35½-23-34½.

Following their wedding, Yukie accompanied her new husband on their honeymoon. However, a significant archaeological discovery prompted him to remain at the excavation site, causing Yukie to return home early. Consequently, she resided with Akira and her three daughters without her spouse present. Her somewhat unreliable personality contributed to Akira feeling he needed to assume a leadership role in the household.

A pivotal moment occurred when Akira was discovered in a compromising situation with Yukie, specifically sharing her bed. This incident immediately preceded Akira finding a mystical artifact in his father's study, setting the core plot in motion.