"Oyayubihime Infinity" is a manga series that blends elements of romance, fantasy, and psychological drama. The narrative centers around Tsubame Mikogami, a high school girl who becomes entangled in a surreal and emotionally charged world after encountering a mysterious boy named Itsuki. Itsuki possesses the ability to create miniature worlds within his fingernails, each reflecting the inner struggles and desires of the people he encounters. These worlds, known as "Thumbelina Worlds," serve as a metaphor for the characters' psychological states, often revealing hidden traumas, fears, and aspirations.

Tsubame is drawn into these worlds when Itsuki offers to help her confront her own unresolved pain. As she navigates these intricate, dreamlike environments, she begins to uncover the truth about her past, particularly her relationship with her late mother, who died under tragic circumstances. The story explores themes of grief, identity, and the power of human connection, as Tsubame and Itsuki form a bond that transcends the boundaries of reality and imagination.

The series also delves into the lives of other characters who interact with Itsuki's Thumbelina Worlds, each with their own emotional burdens. These characters include Tsubame's classmates and acquaintances, whose personal struggles are brought to light through their experiences within the miniature realms. The narrative weaves together their individual stories, creating a tapestry of interconnected lives and shared emotional journeys.

Itsuki's role as the creator of these worlds is central to the plot, and his motivations remain enigmatic for much of the series. His ability to manipulate reality within the Thumbelina Worlds raises questions about the nature of truth, perception, and the human psyche. As Tsubame grows closer to Itsuki, she begins to unravel the mysteries surrounding his existence and the origins of his powers, leading to a deeper understanding of both herself and the world around her.

The manga balances its fantastical elements with a grounded exploration of its characters' emotional landscapes, creating a story that is both visually imaginative and thematically rich. The interplay between the real world and the Thumbelina Worlds serves as a narrative device to examine the complexities of human emotions and relationships, making "Oyayubihime Infinity" a compelling and thought-provoking series.