"Gotcha!" centers on a group of high school students who become entangled in a mysterious game that blurs the line between reality and fiction. The protagonist, Riku, is an ordinary teenager who stumbles upon a strange app on his phone after receiving an anonymous message. The app, called "Gotcha!", challenges players to complete a series of tasks within a set time limit. These tasks range from mundane activities to increasingly dangerous and surreal challenges, each tied to cryptic clues and riddles. As Riku and his friends delve deeper into the game, they discover that failure to complete a task results in severe consequences, including physical harm and even disappearance.

The narrative unfolds as Riku teams up with his childhood friend, Yuna, and a tech-savvy classmate, Hiroshi, to uncover the truth behind the app. Along the way, they encounter other players, some of whom are willing to sabotage others to ensure their own survival. The group learns that the game is orchestrated by a shadowy organization with unknown motives, and the tasks are designed to test the players' limits, both mentally and physically. As the stakes escalate, the characters are forced to confront their fears, insecurities, and moral dilemmas, revealing deeper layers to their personalities and relationships.

The story is driven by a mix of suspense, psychological tension, and action, with each episode introducing new challenges that push the characters to their breaking points. Themes of trust, loyalty, and the consequences of one's choices are explored as the group navigates the increasingly perilous game. The plot builds toward a climactic confrontation with the game's creators, culminating in a resolution that ties together the mysteries introduced throughout the series. The characters' growth and the unraveling of the game's secrets form the core of the narrative, making "Gotcha!" a compelling exploration of human resilience and the darker side of technology.