Perfect Memento in Strict Sense: Memorizable Gensokyo

Within the human village of the hidden land of Gensokyo, there exists a clan whose purpose is to record the history of its residents, whether they be human or youkai. Every 120 to 180 years, a Child of Miare is reincarnated, retaining all of their past lives' memories. However, they also lack long lifespans, rarely living beyond the age of 30. As the ninth Child of Miare, Hieda no Akyuu works on the ninth Gensokyo Chronicle—but soon begins to think about the reality of her existence—which has been extensively long, yet at the same time, minutely short.