"M.E.M. - Yogosareta Junketsu" is a science fiction anime series set in a dystopian future where humanity is under constant threat from mysterious entities known as "Erasers." These beings possess the ability to erase individuals from existence, leaving no trace of their presence. The story centers around a group of young individuals who are recruited into a secretive organization called M.E.M. (Memory Erasure Management), tasked with combating the Erasers and protecting humanity's memories, which are the key to their survival.

The protagonist, Aoi Shirogane, is a high school student who becomes involved with M.E.M. after a personal encounter with an Eraser. Aoi discovers that she possesses a unique ability to resist the Erasers' powers, making her a crucial asset to the organization. Alongside her are other members of M.E.M., each with their own specialized skills and tragic backstories tied to the Erasers. These include Kaito Tachibana, a skilled combatant with a stoic demeanor, and Yuna Hoshizora, a tech-savvy strategist who harbors a deep-seated fear of losing her memories.

The narrative unfolds as the team investigates the origins of the Erasers, uncovering a complex web of conspiracies involving government experiments and the manipulation of human memories. As they delve deeper, they learn that the Erasers are not merely mindless destroyers but are connected to a larger, more sinister plan that threatens the very fabric of reality. The series explores themes of identity, memory, and the ethical implications of altering or erasing human experiences.

Throughout the series, the characters face moral dilemmas and personal challenges, particularly as they confront the possibility that their own memories may have been tampered with. The tension escalates as the team uncovers the truth about M.E.M.'s true purpose and the role they are meant to play in the ongoing conflict. The story builds toward a climactic confrontation with the Erasers' mastermind, revealing the ultimate cost of preserving humanity's memories and the sacrifices required to ensure their survival.