"ARISA" is a psychological mystery anime centered around Tsubasa Uehara, a high school student who becomes deeply involved in unraveling the secrets surrounding her twin sister, Arisa. The story begins when Tsubasa transfers to Arisa's school after her sister attempts suicide. Arisa, known as the "princess" of her class for her kindness and popularity, is left in a coma, leaving Tsubasa determined to uncover the truth behind the incident.

Tsubasa discovers that Arisa’s class participates in a secret ritual called the "King's Time," where students anonymously write down their wishes, and the "King" grants one wish per week. Initially, the ritual seems harmless, but Tsubasa soon realizes it has a darker side, as the wishes often lead to manipulation, blackmail, and even violence among the students. The class is bound by a strict code of secrecy, and anyone who breaks the rules faces severe consequences.

As Tsubasa investigates, she uncovers layers of deception and hidden agendas within the class. She learns that Arisa had been trying to stop the King's Time, believing it was causing harm to her classmates. Tsubasa’s efforts to expose the truth put her in danger, as she becomes a target of the King and the class’s collective hostility. The narrative explores themes of trust, betrayal, and the psychological toll of group dynamics, as Tsubasa navigates a web of lies to save her sister and bring the King's Time to an end.

The main characters include Tsubasa, whose determination and loyalty drive the story forward, and Arisa, whose absence looms large as the catalyst for the events. The classmates, each with their own secrets and motivations, play crucial roles in the unfolding mystery. The King, whose identity remains shrouded in mystery for much of the series, serves as the central antagonist, orchestrating the chaos within the class.

The plot is tightly woven, with twists and revelations that keep the tension high. The story delves into the psychological manipulation and moral dilemmas faced by the students, highlighting the consequences of their actions. Through Tsubasa’s journey, the series examines the complexities of human relationships and the lengths people will go to protect themselves and others.