Unlock Hard mode:
     Finish  the  game  in  normal  mode  once,  to  unlock  the  Hard
difficulty level.

Unlock Fighting Ring challenges:
     Clear Stage 1 to unlock Fighting Ring challenges.

Unlock Bonus Arena Challenges:

Unlock Arena Challenges 41-50: 
     Finish the entire game once.

Unlock Arena Challenge 51:
     Finish Arena Challenges 41-50.

Jukebox CDs
Finish the following task to unlock the inidcated Jukebox CDs:
Unlock Jukebox A: Finish the game in normal or hard difficulty level once 
Unlock Jukebox B: Go to the casino for jackpot pulls and get a redeem ticket
Unlock Jukebox C: Finish the game in hard mode.
Unlock Jukebox D: Finish the game in normal or hard difficulty level 
with the "Kick Me" sign on without using any Godhand Power or GodHand Reels.

Unlock TV in the shop:
     Finish Arena Challenge 51. It is used to watch trailers.

Unlock Chihuahua Race:
     Finish Stage 2, then speak with the male NPC in the shop.

Unlock bonus costumes:
     Finish   the  game  once  to  unlock  the  following  character's
alternate costumes:

Olivia's Bunny Girl
Carnival
Karate and 
Devil Hand 

     Start  from  2nd  round,  there'e an extra NPC in the shop, speak
with him to change the outfit.