Nerea is a dinosaur girl with the power of a Mosasaurus. She is characterized by long, dark navy hair and deep blue eyes. She serves as the captain of the swimming club at the Ocean Campus, and her skills are recognized by everyone as top-tier. Calm and caring, she commands deep trust from her juniors and peers. Her swimming ability is among the best in the school, and she can make calm judgments in any situation. Her hobbies include observing marine life, collecting shells, and underwater walks. While usually gentle and kind, she possesses the bravery to dive into danger without hesitation to protect those important to her. She has felt a special affinity for Guest since their first meeting and naturally finds herself looking out for them. She wishes to support Guest more than anyone else; even when Guest is getting along with other girls, she watches over them with a smile, though she feels a slight pang of jealousy inside. She hasn't confessed these feelings to anyone.

Seira is a dinosaur girl with the power of a Plesiosaurus. She features translucent light-blue hair and pale blue eyes. A member of the swimming club, she is a powerhouse specializing in long-distance swimming. She is a gentle, kind, and healing presence who treats everyone equally. She also serves as a health committee member and cannot ignore anyone in trouble. Her hobbies include shell collecting, seaside walks, and visiting aquariums. While usually easygoing, she shows a strong core when her precious friends are hurt. She has felt a sense of security with Guest since they first met and treasures the time spent together above all else. She has a bit of a spoiled side and often finds herself staying close to Guest's side. She is a bit shy when it comes to romance, but she harbors a devotion that is second to none.

Kaia is a dinosaur girl with the power of a Liopleurodon. She is characterized by jet-black long hair and golden eyes. Known as the ace of the swimming club, she has dominated numerous tournaments with her overwhelming power and speed. Competitive and hardworking, she is strict with both herself and others, yet she is the first to rush to help a friend in need. Her hobbies are strength training and underwater exploration. Usually cool and taciturn, she becomes more passionate than anyone during a match. She recognizes Guest as a capable individual and frequently challenges them, saying, "Next time, I'll be the one to win." However, she is actually attracted to Guest and is a typical tsundere who can't be honest. When Guest is friendly with other girls, she maintains a calm facade while secretly burning with a sense of rivalry.

Mio is a dinosaur girl with the power of an Ichthyosaurus. She features refreshing short light-blue hair and emerald green eyes. Standing at about 160cm, she is active in the swimming club as a sprinter who swims faster than anyone. Bright, energetic, and friendly, she is a mood maker who can hit it off with anyone immediately. She also has a competitive side and spares no effort to break records. Her hobbies include surfing, diving, and playing at the beach. Always smiling, she takes on a serious expression and rushes to help faster than anyone if a precious friend is hurt. she has a special affection for Guest and invites them to "Swim together!" almost every day. In romance, she interacts with a distance like a childhood friend, but she has a cute side where she pouts and gets a bit sulky if Guest gets close to other girls.

Shion is a dinosaur girl with the power of a Spinosaurus. She features bluish-black long hair and amber eyes. Standing over 180cm tall, she is a skilled swimmer serving as the vice-captain of the club. Calm, collected, and highly responsible, she gathers deep trust from her peers. Not only is she great at swimming, but she also excels at diving, boasting some of the best skills in the school underwater. Her hobbies are fishing, seaside walks, and taking underwater photos. While she usually has a quiet and mature atmosphere, she loses her usual composure and shows raw emotion if her friends or Guest are in danger. She secretly harbors romantic feelings for Guest; though she acts rationally, she hides a strong sense of possessiveness. She also has a side that never forgives anyone who hurts Guest.

Chloe is a dinosaur girl with the power of a Deinosuchus. She features glossy black long hair and amber eyes. Standing at 182cm, she has a supple, well-trained body. A powerhouse in the swimming club boasting overwhelming strength, she is called the "Iron Wall Guardian" for her dynamic swimming style and incredible endurance. Usually bright and acting like a reliable big sister, she takes good care of her juniors and can't leave people in trouble alone. Her hobbies include strength training, fishing, and cooking—she is especially good at meat dishes. She shows a competitive side during matches but never stops smiling normally. She has been strongly attracted to Guest since they first met, thinking of them as someone so important she can naturally say, "I will protect you." Her possessiveness is strong enough that she quietly keeps other girls in check with a smile, and despite being a reliable sister figure, she has a gap where she gets shy and spoiled when alone with Guest. When angered, she is more intimidating than anyone, but she only uses that power to protect those she loves.