Final Chapter...
	New Game Plus...
	Recruit Mech-Hisui...
	Recruit Satsuki...

Get all Battle Masteries to unlock the final chapter. Also, you can unlock two new characters for New Game Plus when you finish this chapter.

Unlockable	How to unlock
Final Chapter	Get all Battle Masteries
Unlock two characters for New Game Plus	Finish Final Chapter

Beat the game. Also, upon finishing the game, one can increase difficulty 1-10; as well as add a special item that increases stats. Unused stat points also carry over.

Unlockable	How to unlock
Change difficulty	Beat the game.
New Game Plus	Beat the game.
Stat Boosting item	Beat the game.

In Stage 47 of Haruna route, If Kohaku and Hisui have a combined kill count of 50, then Mech Hisui will join you.

You can get her at the end of stage 29 of Takumi's route. You have to kill her twice with Shiki. She appears in stages 5, 20 and 21.