Onigri shines as an action-focused MMORPG, but a few issues prevent it from being the best in its class.
All in all Onigiri is just not a good game. There are really no redeeming qualities unless you really like manga, more than solid gameplay, and enjoy repetitive grinding in uninspired worlds. If you're looking for a manga-inspired game than there are solidly better choices already on the market such as Dragon Nest and Elsword. Neither of those games are perfect either, but at least they're not the crapshoot Onigiri is.
The first 15 minutes of Onigiri does all it can do to put you off. Press on through this however, and there is a surprisingly deep game to be found, one with a very good story centred around good and evil.