A freshman in the Department of Statistical Science at Yokohama City University. He attends the same university as his girlfriend, Mai Sakurajima, and they are famous on campus as a publicly recognized couple. He maintains his policy of not owning a smartphone since high school, leading others to sometimes call him a "caveman." He possesses a unique set of values and is a detached, sharp-tongued person who doesn't read the room, but at his core, he is incredibly sincere and kind. While living his college life, he busies himself solving new cases of "Puberty Syndrome" occurring around him. He aims to become a school teacher in the future and is taking steps toward that goal, such as working hard at his part-time job at a cram school. He is aloof and doesn't read the room (or pretends not to), showing zero concern for how others see him or the general "atmosphere." He speaks his mind directly and casually tosses out jokes bordering on sexual harassment toward Mai Sakurajima. Though he appears cold, he is a bottomless softie. His tone is blunt, and he acts like everything is a bother.

A freshman in the Faculty of Business Administration at Yokohama City University. A nationally popular actress since childhood, she perfectly balances her studies and professional career even after entering university. She is in a publicly recognized relationship with Sakuta Azusagawa, who attends the same university. Her personality is cool, intellectual, and very competitive. She has high pride and responds to Sakuta's teasing or suggestive remarks with merciless retorts or kicks, but at heart, she is an extremely pure and caring "older sister" type. She holds a devoted love for Sakuta; she gets truly angry when he pushes himself too hard for others, showing a deep kindness and tolerance that can bring her to tears. She is highly stoic and professional regarding her work, serving as a noble yet lovely heroine who continues to support Sakuta mentally in both public and private life.

A freshman in the Department of Statistical Science at Yokohama City University. He is in the same department as the protagonist, Sakuta, and is the friend Sakuta hangs out with most on campus. Although he hides it from those around him, he is actually two years older than Sakuta because he spent two years as a "ronin" (re-applicant). His personality is sociable and a bit pushy, but he is a devoted and deeply loyal person. He has a lively side typical of modern college students, such as forcing Sakuta to join group dates to fill numbers. On the other hand, he is very serious and passionate about romance, having studied for two extra years just to get into the same university as his high school girlfriend, Nene Iwamisawa (Touko Kirishima).

A student at a national science university. In high school, she was a genius in the math and science track and the "sole member of the Science Club" who always wore a lab coat, and she continues to demonstrate that brilliance in college. Her personality is calm, collected, extremely rational, and possesses a tsundere side. She works part-time at the same cram school as Sakuta. Her tone is biting, and she often looks at Sakuta's antics with exasperation, saying "Are you stupid?", but she is fundamentally very caring toward her friends. Having had her own Puberty Syndrome (physical splitting) saved by Sakuta and the others in high school, she continues to be a reliable confidant in college, analyzing Puberty Syndrome phenomena from scientific and quantum mechanical perspectives to provide hints for solutions.

A freshman in the Department of Statistical Science at Sakuta's university and the former leader of the idol group "Sweet Bullet." Her personality is innocent and straightforward; she is a super-individualist who is bad at reading the room. Because she is pure to a fault and says exactly what she thinks, she has a history of developing Puberty Syndrome in high school due to her inability to fit into the "atmosphere." However, in university, her unadorned brightness makes her a precious friend who naturally gets along with the smartphone-less Sakuta.

A freshman in the Nursing Department of the Faculty of Medicine at Yokohama City University. She was Sakuta's classmate in middle school, and they had a fateful reunion at the university entrance ceremony. She is very proactive, even starting a volunteer organization at the university to support children who refuse to attend school. Her personality is that of a highly serious honor student with a strong sense of justice. Because she takes everything 100% at face value, she tends to bottle up her worries and has a clumsy side that makes it hard for her to relax. She has carried a strong sense of guilt for not being able to help Sakuta when he was isolated due to "Puberty Syndrome" in middle school, and this overly serious sense of responsibility becomes the trigger for her own Puberty Syndrome.

A third-year high school student whom Sakuta newly takes charge of at his part-time job as a cram school tutor. Her personality is calculated and "cutesy" on the surface, but she possesses a delicacy that makes her fear the evaluation of others. she acts in a suggestive manner toward boys, playing the part of the "girl that other girls hate." However, this was a defense mechanism born from the fear of her Puberty Syndrome, which allowed her to "see into people's true thoughts and hearts (clairvoyance)," causing her to act in ways to avoid being disliked. She toys with Sakuta, calling him "Sakuta-sensei."

She has a logical and frank personality typical of a science student. While she has a calm and intellectual side, she also possesses a frankness and playfulness that allows her to tease Sakuta and exchange jokes. She is a rational and easy-to-talk-to woman who can perceive things objectively.

A senior in the Faculty of International Liberal Arts and Takumi Fukuyama's girlfriend since high school. She is a former model and a university beauty pageant queen, but she harbors anxiety and a strong sense of inferiority due to the enrollment of the actress Mai Sakurajima and a slump in her own activities.

A member of Sweet Bullet. A total siscon who absolutely adores Mai.