MAX Cheat Zone

Dead Or Alice 2: Hardcore

Unlock Bayman:
Complete Story Mode with every character. Or Complete Story Mode using any combination of characters 30 times.

Unlock Tengu:
Collect 10 stars in Survival Mode. Or Play as any combination of characters more than 200 times.

More costumes:
even more than four costumes, just keep playing and you will get as many as 8 for some characters. I have not been able to isolate what needs to be done exactly but just keep playing and you will have a lot of cool costumes