In the Japanese version, you need to enter your name and select a blood type before the game starts. Depending on selected blood type, you'll have different parameters on your character. The available blood types are RH+ A, B, O and AB - at least initially. While selecting the blood type, press Up + A + B on controller 2 and RH will change to RH-, now the whole set of blood types will be different: RH- in addition to the normal A, B, O and AB. RH-'s parameters are higher than RH+.