(found towards the end of the name entry list 
of characters) as a name to unlock an extra 
menu at the options screen and 44 levels. 
The extra options are: 

Riki's shot trail thickness: Normal (thin)/Thick 
Mami's shot trails:          Normal (thin)/Thick/Large 
                             Missile/Thick (Nintendo 64 style) 
Explosion Fragments:         Normal/None/Heavy 
Background:                  Normal/None/? 
Invincibility:               On/Off