Play as Moe:
Successfully complete dramatic mode after defeating Moe in the final match.

Play as Mona:
Successfully complete dramatic mode after defeating Mona in the second to last 
match.

Bigger chests:
Successfully hit all 100 balls in practice machine mode to unlock the Patto. 
Equip this item on a character to increase her chest size.

Zenshin Taitsu costume:
Unlock Mona and Moe, then defeat all opponents in free play mode as any girl.