Origin of name: "Sea" alone is lame... I know, let's add "na."
Ability: Basically controls water and ice.
Special moves: "Ice Prison" – traps in a cage of ice. "Aqua Storm" – washes away enemies in one go.
Fighting style: Area attack / suppression type.
Appearance: A mermaid-line long dress with a large floral decoration at the chest, and an overskirt made of sheer chiffon material draped from the shoulders and waist.
The person inside seems to be a very ordinary female college student.
She is also the captain of the Yokohama branch. The name of the person inside is Kurokawa Anna.

Ability: Manipulates plants.
Skill: "Flora Garden" – buffs and heals all allies.
Fighting style: Recovery / support.
Appearance: A country-style A-line dress that looks like a white puff-sleeve blouse paired with a green corset. Real acorns and bells hang from the waist belt, and the hem is lavishly embroidered with four-leaf clovers.
The person inside is an ordinary high school girl. The name of the person inside is Kawasaki Rina.

Ability: Burns with the power of the sun.
Skill: "Sun Blade" – creates a blade from sunlight to cut through in one stroke.
Fighting style: Just cut things.
Appearance: A high-waist flared mini dress with boldly placed golden sun symbol motifs on the chest, waist, and both shoulders. Asymmetrical frills and active short boots make for a classic idol-style design.
The person inside is an ordinary male high school student. The name of the person inside is Yoshimura Daichi.

Ability: Controls rocks and earth.
Skill: "Rock Fortress" – creates an absolute defense zone to protect allies.
Appearance: Based on a slim, tight mini dress that allows for active movement, with rugged rock and raw gemstone parts fixed at the chest and waist. Vines are wrapped around the upper arms and thighs, creating a combat-oriented survival design.
The person inside is Shirakawa Hitomi, an ordinary female college student.

Ordinary people. Appear in appropriate scenes.

Classmates in you's class.
Appear in appropriate scenes.

Male.
you's best friend.
Classmate.