Unlock Duke as a Playable Character:
Complete Story mode with Soiree and Alba.

Unlock Alternate Costumes:
Finish a challenge in 'Challenge' mode.

Unlock Show Time Stage:
Beat 10 challenge mode missions.

Unlock Esaka Stage:
Beat 25 Challenge mode missions.

Unlock Infernal Gate Stage:
Beat 25 Challenge mode missions.´

Unlock Cemetery Stage:
Beat 40 Challenge mode missions.

Unlock Fighter Profiles:
When you complete the game the corresponding character will be unlocked at the 'Profile' screen along with their Rigging Model which you can use in game by selecting it through the Profile.

Cemetery Stage:
Complete successfully all 'Challenge' mode missions.

Show Time Stage:
Complete successfully 10 'Challenge' mode missions.

Esaka Stage:
Complete successfully 25 'Challenge' mode missions.

Infernal Gate Stage:
Complete successfully 25 'Challenge' mode missions.

Play as Duke:
Complete successfully 'Story' mode with Soiree and Alba.

Alternate Costumes:
Complete successfully 'Challenge' in 'Challenge' mode.

Extra Hits:
Use Ryo's Whiplash Bash with Light Punch to get 30 hits in of the 'Challenge' mode missions. Then use his Level 2 Special.