Sasami-san@Ganbaranai

Sasami Tsukuyomi is a hikikomori, content to live her life entirely within the confines of her room, never venturing outside. Her only window to the world is a "Brother Surveillance System," which allows her to observe her older brother, Kamiomi, and his interactions with the three beautiful, powerful Yagami sisters. Sasami believes she's simply living a quiet, unassuming life, but the reality of her family and the world around her is far stranger than she could ever imagine. What begins as a seemingly mundane, albeit voyeuristic, existence quickly spirals into a series of increasingly absurd and fantastical events. As deities, alternate universes, and the very fabric of reality begin to unravel around her, Sasami finds herself at the center of a cosmic comedy, forced to confront her own anxieties and the bizarre truths of her extraordinary lineage. Can this reclusive girl truly remain a bystander when the fate of the world, and perhaps even her brother, rests in her unwilling hands?

✦ AI-drafted summary