Tokyo’s MediBang! and Manga CPO have joined forces for a new contest with two sections, Manga and Illustration. They want a max. 32-page manga style comic, and / or an unpublished comic-style illustration on the theme of “Journey”. Free entry, and it appears to be open worldwide though they obviously expect to see a Japanese style in the entries. Deadline: 7th May 2019.
MediBang appears to be a sort of store platform for indie manga creators to sell their comics and illustrations in the Japanese market. They also offer the free MediBang Paint software, now fairly mature at version 23.x, and Jump Paint which is more of a guided experience with embedded tutorials for new manga creators. The contest doesn’t appear to restrict you to just this software.