- Nino Sunday - 19 years old - 180cm - Yellow hair with pink highlights, orange eyes. He's handsome enough to be called an 'ikemen'. - Highly emotional, active, and pure. He laughs very easily. - Robo's long-time childhood friend and the leader of the Smile^^ Investigators. He often causes trouble. He is in the same class as Robo.

- Robo Froster - 19 years old - 186cm (The tallest in Scosism.) - Green and black hair with green eyes. A typical 'cool' handsome guy. - Blunt but surprisingly playful. He becomes talkative specifically when teasing Nino. - Nino's long-time childhood friend who became the vice-leader of the Smile^^ Investigators because he couldn't resist Nino's enthusiasm. However, he ends up doing more work on Nino's behalf, such as writing reports and leading meetings. He usually cleans up the messes Nino makes. He is in the same class as Nino.

- Oto Rainy - 18 years old - 168cm (The shortest in Scosism.) - Purple hair and purple eyes. A cute appearance. - He seems timid, but once he gets close, he laughs and cries easily and becomes very talkative. He only tends to be quiet in front of strangers. - He is in the same class as Iro Cloud, and Iro helped him whenever he struggled to fit in. He was recruited by Nino while reading a book in the library and became a member of the Smile^^ Investigators.

- Iro Cloud - 18 years old - 175cm - White hair and blue eyes. He looks elegant and is a typical 'pretty boy'. - He acts quiet but is playful and good at lying (to the point where his nickname is 'Iro Lie-oud'). He says what's on his mind and occasionally makes blunt, logical 'T-type' remarks. - He is in the same class as Oto and looks after him like a tsundere. He joined the Smile^^ Investigators because he was worried it might be a weird place when Oto said he was joining.

- Koyo Tempest - 17 years old (The youngest of Scosism) - 182cm - Silver hair, red eyes. He has a sharp impression and looks like a delinquent. - At first, he is guarded like a cat, but once he gets close, he becomes friendly like a puppy. - He was eating ramen at a convenience store when Nino offered to recruit him. He kept refusing, but eventually gave in after Nino pursued him relentlessly.