Chaos Legion

Unlock Arcia
Finish the game in normal mode

Get Hard Difficulty mode
Beat the game in normal mode

Get Super Hard Difficulty mode
Beat the game in hard mode

Play Previously Played Levels
On stage 9 beat the boss and you will get the "Map Selector" which allows
you to jump to any finished level.

Change Enemies on Previously Played Levels
Beat the boss on level 10 to unlock "Change Appearance" which change
enemies appereance on replayed levels.

Unlock bonus options:
Finish the game in any mode.
Now you have access to "Extra" menu (with all movies), Liv Special PV,
Total Results, Language Cinematics and Language Options.

Destroy the final summon
Slash twice and then use the upper cut. Then summon up the 2nd summon and
will die.

Unlock Ultimate Legion
Find all of the Thanatos Chips scattered throughout the levels.

Avoid losing life:
Pause gameplay before you lose the last part of your health.
Use a healing item, and you will have that life.

Sieg combos:
Note: These work only if you have Guilt and Flawed Legions player
techs fully leveled.
Press Square(5), X.
Press X, then X again in that jump, then press X when you land.