If you want a service to create and refine anime art with upscaling and variation options, niji・journey is a great option. This AI-powered tool lets you create high-quality anime images based on prompts you define. It's got upscaling and variation tools to refine the output, and it's for personal or commercial use, with premium subscription options.
Another tool worth checking out is Anime Art Studio, a free, web-based service with more than 100 stable diffusion models for creating anime images, voices, videos and animations. It's got tools like image upscaling, prompt generation and text-to-video conversion to help you get what you want, and it's designed to keep you happy with high quality and performance.
If you want something a bit more accessible, starryai offers a more intuitive interface to create images based on prompts you type in. It's got options to upscale and refine existing images, and you can customize with options like prompt styles and fine-tuning. With a big library of styles and a powerful API, starryai is good for both casual users and pros.
Last, cre8tiveAI has a full SaaS platform with image and video editing tools, including an Anime Art Painter tool for generating anime backgrounds and other illustrations. It's designed to make the creative process easier with advanced tools available to anyone, so it's a good option for design pros and hobbyists.