Fur is the reason this collection is worth the time. Drawn as a mass of tonal shifts rather than individual hairs, it rewards short overlapping strokes and punishes flat filling — and the grayscale already tells you where the light lands.
Cats appear here two ways: as a companion in a portrait, curled against a girl's shoulder, and as the character themselves — Puss in Boots, the goggled Aviator Cat, a steampunk cat girl.
If you have only colored people until now, a cat is the friendliest place to learn texture.