Megumi Etou is a minor character in the Battle Royale story, assigned the number Girl #3. She comes from a normal family that includes her parents and an older sister, about whom rumors of promiscuity circulate, though Megumi knows these rumors are false. Her background includes being a frequent target of bullying, particularly from Hirono Shimizu, who would trip her or slash her skirt with a razor in the hallways. In the novel and manga versions, Megumi is close friends with Mizuho Inada and Kaori Minami, while in the film adaptation she is best friends with Noriko Nakagawa. In the novel and manga, she harbors a crush on Shuya Nanahara, but in the film her romantic interest shifts to Shinji Mimura. Her hobby in the film is photography, using a Polaroid camera to take pictures of Shinji and of Noriko, Shuya, and Yoshitoki Kuninobu on the bus before the game begins.

Megumi is described as shy, playful, and overly trusting in others. Her trusting nature proves to be her fatal flaw. When the Battle Royale program begins, she hides in an abandoned house in a residential area, still carrying her cell phone, which her parents gave her to use in an emergency. Believing the authorities cannot track mobile signals, she attempts to call her parents for help, but the teacher, Kinpatsu Sakamochi (or Yonemi Kamon in the manga), answers and reveals that all phone lines are under their control. Shortly after, she hears someone enter the house and hides under a kitchen table. The intruder is Mitsuko Souma, a girl with a reputation for being part of a mean clique linked to her bully Hirono. Megumi considers trying to kill Mitsuko, but her cell phone rings again, revealing her hiding spot. In the novel, the call from Sakamochi alerts Mitsuko; in the manga, Megumi crushes the phone with her hand, but the broken device on the floor draws Mitsuko’s attention. In both the novel and manga, Mitsuko approaches Megumi while feigning fear and requesting they team up. Believing Mitsuko’s act, Megumi embraces her, at which point Mitsuko slits her throat with a kama sickle. In the film, Megumi initially pulls a stun gun when Mitsuko enters, but after a brief conversation, Mitsuko lures her into a false sense of security, then chases her and kills her by slashing her throat, explaining that she found two classmates who committed suicide but will not die that way herself. In all versions, Megumi is the first victim of Mitsuko Souma and the fifth student to die in the manga.

Megumi’s primary motivation is survival, and she attempts to achieve it through calling for rescue and seeking an alliance, but her inability to recognize deception and her misplaced trust lead directly to her death. She has no special combat abilities or strategic skills; her assigned weapon is an army knife in the novel and manga and a pot lid in the film, though she never uses either effectively. Her role in the story is to serve as an early casualty that highlights the cruelty of the game and introduces Mitsuko’s manipulative ruthlessness. Her relationships are limited to her friendships with other girls and her crushes on boys, yet none of these connections save her. Megumi undergoes no significant development because her death occurs early, but her brief appearance underscores the theme that innocence and trust are fatal in the brutal contest.