Successfully complete the indicated task to unlock the 
corresponding character:

Onikage: Successfully complete level 30 with Rikimaru. 
Kagura: Successfully complete level 25 (defeat Shigi) with Tesshu. 
Nasu: Successfully complete level 1 with Ayame. 
Rin: Successfully complete level 1 with Rikimaru. 
Tenrai: Successfully complete level 10 (defeat Tatsumaru) with Ayame. 
Tesshu: Successfully complete level 20 (defeat Juzo) with Rin.