Find the main function and the getopt or getopt_long loop. Add the new case.
Pro trick using jot and random (Linux):
If you are SSH'd into a server without X11, you cannot change fonts locally. However, you can use fbterm (Framebuffer Terminal) to load Japanese fonts directly from the Linux console. cmatrix japanese font
Note: matrix[j][i].val in standard cmatrix is typically a char (1 byte). Japanese characters are multi-byte (UTF-8). You may need to change the storage structure or handle multi-byte rendering if the original code strictly enforces 1-byte chars. However, modern terminals handle UTF-8 output strings well if you print the specific string rather than a single char. Find the main function and the getopt or getopt_long loop