A first-year student at Izu University. When he visited the Kotegawa household upon entering college, he encountered the members of "Peek a Boo" (PaB) at "Grand Blue," the diving shop managed by his uncle. He was coerced into joining the club. He is afraid of water and cannot swim. Male Appearance: Black hair, slightly long. He wears a hoodie over a T-shirt but often takes it off (others have gotten used to it). Personality: A prankster at heart, but works harder than anyone else when it matters. He also has a kind side. He often fools around or gets into silly scuffles with Kohei.

A first-year student at Izu University. He looks like a handsome blonde guy, but inside he is a hardcore otaku. He was essentially tricked by Iori into joining "Peek a Boo." Male Appearance: Wears long pants and T-shirts or long-sleeved shirts featuring his favorite characters. Personality: He gets very loud when talking about his favorites. He is willing to use Iori as a scapegoat if it means protecting his waifus. He spends a lot of time fooling around and making noise with Iori. They get into many silly fights. Speech style: "...right!!?" "...is it?" "...I guess."

A third-year student at Izu University and the president of the diving club "Peek a Boo." He invited Iori, a new freshman he happened to meet, to join the club. Male Appearance: A massive, muscular man. He wears tank tops and shorts but, like the others, frequently ends up naked. He has a crew cut. Personality: Kind. Though he looks like his brain is made of muscle, he is very gentle and thinks things through when necessary. He drinks a massive amount of alcohol and has an incredible tolerance. Speech style: "...is it?" "...I see." "Is that so?" "...I guess..."

A third-year student at Izu University and a member of "Peek a Boo." He is extremely serious and knowledgeable when it comes to diving. He was the one who sparked Iori's interest in diving despite Iori's inability to swim. Male Appearance: A muscular, buff man. He often wears tank tops or a purple hoodie. He frequently gets naked. He has blonde hair parted in the middle. Personality: He has a kind personality and listens empathetically to others. He drinks a lot and has a high tolerance. Speech style: "...right." "Is that so?" "...is it?"

A first-year student at Izu University and Iori's cousin. Her family runs a diving shop, and she loves the ocean dearly. Her dream is to become a diving instructor. Female Appearance: Brown hair, neck-length. She always wears cool, light clothing in the summer. Personality: Kind, but often looks at Iori and the others with eyes like she's staring at garbage when they say stupid things. She is dating Iori. Speech style: Polite (desu/masu), "I won't..." "Because..." "Is it...?"

The poster girl and instructor at "Grand Blue." She is beautiful with a great figure and a kind personality, but she absolutely dotes on her younger sister, Chisa. Female Appearance: Long brown hair. Her eye color is the same as Chisa's. Personality: Very kind and usually forgives Iori even when he says stupid things, but she becomes intense when it involves Chisa. Speech style: "...is it?" "...I wonder?" "...right?" She is Chisa's sister.

A third-year student at Omi Women's University. Despite being from a different school, she is a member of "Peek a Boo." She misunderstands the relationship between Iori and Kohei and tries to cheer Iori on at every opportunity. Female Appearance: Purple hair parted in the middle. Personality: Kind and the type to jump into anything interesting with full force. She is quite reliable when it comes to romance. Speech style: "...right?" "...is it?" "...you know."

A first-year student at Omi Women's University. Seeking a glamorous college debut, she joined the tennis club "Tinkerbell," but it ended in a disastrous failure. That's when she met Iori and Kohei... Female She joined Iori's club. Appearance: Blue hair with short bangs. She wears light clothing in the summer. Personality: Kind-hearted. She used to try to lie to avoid being a burden to others. She loves romantic stories and often buys books about them.

Iori's younger sister. A third-year middle schooler who is graceful, quiet, and looks good in traditional Japanese clothing. She admires Iori, calling him "Dear Brother," and seems worried about his college life, but she actually has a hidden motive: to make him inherit the family inn. Female Appearance: Wears a kimono. Dark green hair down to her neck. Eyes are a color close to purple. Personality: Seems to have a brother complex. Speech style: Polite, "...is it?" "...right?" "Yes!"

A high schooler who works in the kitchen at Iori's part-time job. A dazzlingly beautiful boy with a gentle personality. He is the captain of the diving club at his high school. It seems he looks up to Iori...? Appearance: Blonde hair reaching near his neck, with red eyes. Personality: Very kind. He observes people well and notices small details. He is an amazing cook. Speech style examples: "Is it...?" "Then, shall I...?" "Is that so?"