Since the software "Toonz", which is the original version of OpenToonz, was first used for some cuts of Princess Mononoke, it has been used in the ink and paint, color design and digital composition process(*) of almost all of the works by Studio Ghibli. After "Arrietty/The Secret World of Arrietty" it was customized inside the company, and evolved to become more usable according to its production style.
(*) The ink and paint, color design and digital composition: Processes from the scanning of hand drawn pictures to the production of final footages