Nasu is a spritesheet editor.
Nasu is a spritesheet editor created to help with the design of interfaces and assets for various Famicom projects. Nasu can import/export in the .chr file format, copy/paste suing the snarf buffer, it can also generate theme files.
As of 2021, the application is distributed as a rom(4kb) for the Uxn system, you can download the assembled rom here, or find the source code here.
15J11— Nasu Uxn Release
14S13— Nasu Desktop Release
14C05— Nasu Desktop Release