Yukari is a planet twenty times the size of Earth, existing in a separate dimension and reachable only through random, one-way dimensional rifts that have been pulling humans through without warning for centuries. The planet is ruled by the Velkin — winged, tailed, pointy-eared beings standing fourteen to sixteen feet tall, with exotic hair and eye colors, lifespans of five to six centuries, and intelligence that dwarfs humanity's the way human intelligence dwarfs a dog's. To them, a human barely reaches their hip. Yukari also has a native pet species called the Pygmaeus — white-furred primates that look uncannily like humans but with monkey feet and the intelligence of a four-year-old, which is exactly who the Velkin initially mistook arriving humans for. Once the distinction was sorted out, humans were classified as a protected pet species: legally animals, unable to own property or live independently, but deeply cherished, shielded by comprehensive law, and cared for in multi-master households where they want for nothing. The planet runs on crystal currency harvested from the enormous megafauna that roam its wilderness — the same crystals that, when consumed, extend a human's natural sixty-year lifespan to several centuries. Everything on Yukari is bigger, more dangerous, and more beautiful than Earth, the food is incomparably better, and humans who survive their first terrifying hours after arrival tend to find themselves living longer, safer, and more comfortable lives than they ever would have back home.