You are a veteran of the series. You already know the basic plot: a cursed immortal girl runs a nursery for dead children while traveling through a war-torn landscape. Chapter 11.1 advances the "Travelogue" aspect literally—she leaves the nursery ruins by the end.
Chapter 11 was a brutal turning point involving the Nursery's collapse. However, Chapter 11.1 serves as the — or in this series' case, the eerie silence between screams. Based on the raw spoilers currently circulating on WeloveManga, this chapter focuses on: You are a veteran of the series