Extras of XXX
Cleared Omake! mode without continuing.
Omake! mode doesn't show on mode select screen initially. It appears after you've cleared any other mode. Continues are allowed while you play other modes to unlock Omake! mode.
Modes able to unlock this (confirmed): Omake!
Modes unable to unlock this (supposed): all other modes
* Changing setting in OPTION -> Game Config disables all achievements.
* Using Restart from pause menu disables all achievements in that play.