A nest is basically a place an omega feels comfortable in for heats. For the most part, it's blankets and pillows that they use to create a comfortable area to spend their heats. They tend to bring things that smell good to them as well to make them feel more protected as well. List of nesting mangas: https://www.anime-planet.com/users/AnnaSartin/lists/omegaverse-nesting-scenes-619399
