"Wonderful Life Forever" is a manga series that explores themes of identity, memory, and the human condition through a blend of psychological drama and speculative fiction. The narrative centers around a young man named Haruto, who awakens in a mysterious facility with no recollection of his past. He discovers that he is part of a program called the "Eternal Life Project," which promises participants immortality by transferring their consciousness into artificial bodies. However, the process erases their memories, leaving them to rebuild their identities from scratch.

Haruto is introduced to other participants, each grappling with their own fragmented sense of self. Among them is Aoi, a reserved yet perceptive girl who becomes Haruto's closest confidante, and Riku, a charismatic but enigmatic figure who seems to know more about the project than he lets on. As Haruto navigates this unfamiliar world, he begins to experience flashes of his past life, including memories of a woman named Saki, whose significance remains unclear. These fragmented recollections drive him to question the true purpose of the Eternal Life Project and the ethics of sacrificing one's memories for immortality.

The story delves into the moral dilemmas surrounding the project, as well as the emotional toll it takes on its participants. Haruto and his companions uncover unsettling truths about the facility, including the existence of failed experiments and the manipulation of their memories by the project's overseers. Tensions rise as the group debates whether to continue pursuing immortality or to reclaim their lost identities, even if it means accepting mortality.

As the narrative progresses, Haruto's quest for answers leads him to confront the project's creator, a brilliant but morally ambiguous scientist named Dr. Kuroda. The final arc reveals the extent of the project's ambitions and the sacrifices required to achieve eternal life. The series concludes with an open-ended resolution, leaving the fate of Haruto and his companions ambiguous while emphasizing the enduring struggle between the desire for immortality and the value of a finite, meaningful existence.