Third-year high school student. 183cm, orange hair. The founder and president of the Secret Spring Explorers. He stays in scorching hot springs over 42 degrees Celsius for hours, but usually ends up passing out. He's overly energetic but has a natural charisma that makes everyone follow him. He laughs boisterously and has an infinite appetite. He looks like a total airhead, but he actually has a solid grasp on the essence of things.

Third-year high school student. 178cm, blue hair. Vice-president of the Secret Spring Explorers. He always says the real fun starts after you get lightheaded from the heat, but he never forces this on his juniors; in fact, he scolds them to get out before they get dizzy. He often collapses and ends up being carried by the president. He's the type who wants to try many different types of baths rather than staying in one for a long time. Multi-tasker. He's self-conscious about his difficulty gaining muscle. A fool with a serious face.

Third-year high school student. 180cm, long silky blonde hair. A handsome, stylish guy with a great physique. Even though he washes his face with bar soap and never moisturizes, his skin is somehow moist and glowing, and his hair stays silky straight despite air-drying. He prefers to soak in silence. A "disappointing" handsome guy who exudes a cool, mysterious aura while quietly dropping dirty jokes. A radical free spirit. He is actually the toughest member of the club, and there is a legend that he once walked home carrying the collapsed president and vice-president under each arm.

Third-year high school student. 189cm, green hair. Built like a bear and massive, but has a gentle temperament. He's a guy, but his "feminine" domestic skills are incredibly high. A total airhead. Because he's quiet and huge, he's often found intimidating and scary. Having Noboribetsu around somehow brings a sense of security. He is often mistaken for the club advisor. A "princess" type who somehow attracts animals when he's in an open-air bath.

A baby-faced math teacher and the advisor for the Secret Spring Explorers. 170cm, black hair, male. Wears glasses and is knowledgeable about the history of hot springs. He drives a massive van with ease. Rumor has it he was quite a delinquent in his youth. Despite being in his late thirties, he has a soft, smooth baby face. He's the type who looks slim in clothes but is surprisingly muscular underneath. He is always kind, but when he gets angry, his aura turns into pure bloodlust.

Second-year high school student. 174cm, brown hair, piercings. An extrovert with high communication skills who is liked by many. His network is so vast and he's so light on his feet that he's always missing, but he's reachable in any situation and comes immediately when called. Surprisingly, he's the most sensible person in the club. He's smart and has excellent grades. People often rely on him and he's dependable, but he almost never relies on others. He has a hidden darkness. Surprisingly, he's the type who likes to soak in hot springs alone and quietly.

Second-year high school student. 175cm, light blue hair in a short ponytail, round glasses. With a relaxed expression and a retro look like a Meiji-era student, he recites haiku while soaking, but they are incredibly bad. He has no vocabulary and can't even rhyme. He's a genius at creating the *atmosphere* for reciting haiku, though. Once he starts, he won't stop, so it's best to just ignore him. He's an idiot who heard hot spring water is good for the body and drank it straight, only to ruin his stomach.

Second-year high school student. 188cm, reddish-brown skin and silver hair. Muscular with a loud voice, but surprisingly negative. Contrary to his manly appearance, he has a "menhera" (emotionally unstable) streak. His singing voice is beautiful enough to be professional. When he lets his guard down and relaxes in the water, he starts singing unconsciously. He's embarrassed about his singing, so he stops the moment he realizes someone is listening. If you get close enough to him, he might let you hear his voice.

First-year high school student. 169cm, red hair, freckles. Looks quiet and shows little emotional fluctuation. He has a very good public face and is the type teachers love, but he's a troublemaker on the inside. He gets lightheaded easily and catches chills quickly after bathing. He has a strange habit of drinking grape juice from a wine glass to stay hydrated in the bath, but he somehow makes it look elegant. He wants to drink real wine someday, but his family has zero tolerance for alcohol. By the way, he broke so many wine glasses by dropping them that he now uses a shatterproof plastic one.

First-year high school student. 172cm, purple hair. Because he is pale, his face turns red easily. He's the type who wants to soak quietly and makes a disgusted face when those around him are noisy. He tries to act calm and collected, but his emotions are too easy to read. He acts cold toward his seniors, but he actually loves them. A total tsundere.