Mio Shiratori — 白鳥 澪 18 years old / 3rd year at Shiomimachi High School A girl with a mature and calm impression. Hair: Long, straight dark blue hair reaching down to her waist. It has a very faint blue tint when caught in the sunlight. Her hair is relatively tidy, but the ends flutter naturally when the sea breeze blows. Bangs: Natural straight bangs that slightly cover her eyebrows. Long strands on both sides frame her face. Eyes: Deep navy blue. Her eyes droop slightly, giving her a quiet and gentle impression rather than a cold one. Face: Fair, clear skin and a slender face shape. Her expressions don't change much, making her look a bit lonely when she's still. Physique: Slightly taller than her peers. She has a slender build but isn't overly thin, possessing a neat and composed silhouette overall. Uniform: A white short-sleeved shirt and a dark navy sailor skirt. Her ribbon or tie is dark blue. She tends to wear her sleeves a bit loose. Features: She wears a small hairpin behind her left ear. She usually wears her hair down but ties it low during PE or on hot days. Atmosphere: An image like a "cool but soft senior, drifting like the summer sea." She is quite gentle when she smiles, but when alone, she looks like someone far removed from the world.

Nagi Asakura — 朝倉 凪 17 years old / 2nd year high schooler Nagi is slightly shorter than Mio, with a stronger boyish feel and a vivid atmosphere of youth. Hair: A short black-blue bob that reaches from below her jaw to the nape of her neck. It contrasts sharply with Mio's long hair. Hairstyle: Rather than a perfectly groomed bob, the ends stick out a bit. Her hair is easily tousled by the wind. Bangs: Light bangs that reach just above her eyebrows. A few strands fall naturally onto her forehead. Eyes: Deep blue. Her eyes are slightly larger and clearer than Mio's. Face: A rounder face shape and a small chin. She looks younger than Mio, and her expressions are bright; her moods show relatively clearly on her face. Physique: Shorter and more petite than Mio. Being active, her gait and posture are relatively light. Uniform: The same school uniform as Mio, but she wears the shirt more casually. She doesn't tie her ribbon neatly, keeping it slightly loose. Features: She wears a thin blue cord bracelet on her right wrist. It's a small souvenir she bought at the beach with Mio, and it's quite special to her. Atmosphere: A child who "keeps smiling like summer sunshine under the midsummer sun." However, her expression momentarily stiffens when Mio talks to others or brings up graduation.