Beholders is probably a retranslation of Observers. They have in fact appeared multiple times throughout the series, mostly in the Hero Arc and at the end of the Pray and Sion arc.
This is probably the first time the numbered chimeras were mentioned. But we had a significant chimera appearing...
Story is about a woman who can't sleep because her neighbor next door keeps crying. She confronts her neighbor one day and the neighbor asks her to sleep with her in the neigbors apartment. Protagonist reluctantly does and they both get a good nights sleep.
Its not "Love thy neighbor". I also...