A single hit from enemy attack means death

Enter the following at the password screen: LDMSLRDD

All healing items turn into temaki sushi

Enter the following at the password screen: SLLMRSLD

Enemies' attack power doubled

Enter the following at the password screen: MSRLSMML

Enemies' defense power doubled

Enter the following at the password screen: SLRMLSSM

Healing items are no longer available

Enter the following at the password screen: DMLDMRLD

Ougi gauge is always full

Enter the following at the password screen: RRDMLSDL

Shuriken no longer available

Enter the following at the password screen: LLMSRDMS

Turtles can carry unlimited number of shuriken

Enter the following at the password screen: LMDRRMSR

Turtles no longer take damages

Enter the following at the password screen: MDLDSSLR

Unlock free battle arenas

Win mission 1 episode 1 - Free battle 1
Win mission 5 episode 2 - Free battle 5
Win mission 5 episode 1 - Free battle 2
Win mission 10 episode 1 - Free battle 3
Win mission 16 episode 1 - Free battle 4

Unlock score attack

Win mission 6 episode 1.

Unlock time attack

Win score attack for the first time.