Mitsuna Hizuki is Ayumi Hizuki's younger sister and one of the four Hizuki siblings. As a first-year student at Akizuki Academy, her petite frame features a notably short stature, slim build, and small breast size, often drawing descriptors like "kid" or "flat-chested." She has brown eyes and brown hair styled in long twin tails with blunt bangs.

Her reserved nature manifests through sparse speech and minimal facial expressions that seldom betray her emotions, a detachment rooted in her upbringing among women. This environment limited her exposure to men, yet she displays no personal concern about this gap in social understanding. Occasionally, she interjects incongruous moments with factual or academic tidbits absorbed from books.

Within the Hizuki family's circumstances, she emerges as a candidate for pregnancy to break the Rindo lineage's ancient curse, positioning her among potential brides for Naoto Rindo. Her daily wardrobe reflects her student life, typically consisting of school uniforms, sport bloomers, and T-shirts.