Kazushi Sudou is a kind-hearted but romantically dense college student in his late teens or early twenties with casual brown hair, an average build, and no officially specified height who finds his platonic, lifelong friendship with two sisters suddenly cross into an explicit physical relationship. Kazushi Sudou is a relaxed, trustworthy, and kind-hearted college student who, despite being hardworking in his daily life, is romantically oblivious and easily overwhelmed by the aggressive physical advances of his childhood friends

Visually, she is a beautiful young woman with long, vibrant orange-blonde hair tied back into a high ponytail, bright blue-green eyes, and a slender yet well-endowed physique. In terms of age, she is a university student in the same age bracket as Kazushi (approximately 18 to 20 years old). Ayane has a sharp tongue and a slightly aggressive, hot-headed personality. She frequently bickers with Kazushi, masks her true feelings with attitude, and acts out impulsively.

Visually, she is a beautiful young woman with shoulder-length, hair, gentle purple eyes, and a voluptuous, well-endowed figure. Age-wise, she is a college-aged student slightly younger than her sister Ayane and Kazushi (approximately 18 to 19 years old). On the outside, Kotone is soft-spoken, polite, and seemingly the more sensible and mature of the two sisters. Beneath her sweet exterior lies a highly mischievous, bold, and calculating side. She is entirely aware of her physical appeal and uses it to her advantage without hesitation.