When you have destroyed the Ultimate Creation in the Demon Realm choose the iron gate door when you are given the choice of three doors at the 'Save' mirror. To open the door you must use the Bishamon O flute on it. Inside you will see the Bishamon Sword jutting out of a wall object that resembles a skull. This sword has an unlimited supply of magic and is very powerful.

When you have collected ALL 20 Flourites (blue rocks) and completed the game save it and a new speed trail mini-game will be unlocked which when you complete will unlock an option to play the regular game with the Bishamon Sword, infinite ammunition, automatic magic regeneration and 99 Soul Absorbers.

Unlock Alternate Costumes:
First you must complete the game and save. After that choose to start a new game and a new option, entitled "Shinnosuke Normal/Special" option will be available. This new special version will mode will put Samanosuke in a Panda costume with a baby panda in a front pocket clapping his hands.

Unlock Onimusha 2 FMV Movie:
First you must successfully complete the game and save. Now Choose to start a new game and a "Special Report" option will be available. This allows a small sequence from the game's sequel to be viewed.