"Do Not Say Mystery" is a mystery manga series centered around Totonou, a socially awkward but highly observant college student with a knack for solving puzzles and uncovering hidden truths. Totonou’s unique perspective and deductive reasoning often place him at the center of mysterious incidents, ranging from small-scale enigmas to complex criminal cases. His ability to notice subtle details and connect seemingly unrelated events allows him to unravel mysteries that others overlook.

The narrative unfolds episodically, with each arc presenting a self-contained mystery while gradually revealing more about Totonou’s past and personality. His interactions with other characters, including law enforcement, acquaintances, and strangers, often serve as catalysts for uncovering the truth. Totonou’s straightforward and sometimes blunt demeanor contrasts with his deep empathy, making him an unconventional but compelling protagonist.

Supporting characters include a variety of individuals who become involved in the mysteries, such as classmates, detectives, and ordinary people caught in unusual circumstances. These characters often provide additional perspectives or challenges that test Totonou’s skills. The series balances its mystery elements with moments of introspection, exploring themes of human behavior, morality, and the consequences of hidden truths.

The plot structure emphasizes logical problem-solving, with Totonou piecing together clues through careful observation and reasoning. The mysteries themselves range from personal dilemmas to criminal investigations, often incorporating unexpected twists and psychological depth. The series maintains a steady pace, allowing readers to engage with the puzzles while gradually building a deeper understanding of Totonou’s character and the world he inhabits.