It has been the 3rd or 4th time that my Onigiri client suddenly crashed, and then starts up with Japanese text while updating. After starting the game, it ends up re-downloading the game content starting from 27%. Is anyone else encountering this problem or have a solution for it?

This is a rather common problem, but there's no official fix at the moment .-.
One of the moderators, Ringo Tarte, mentioned that launchers were getting rolled back. You can copy all your files into a backup file and replace the game files with the backup files (Delete, copy, paste) when the updates starts again. It should return to its normal state afterwards.

Thanks. I actually did that and it had worked.