After you unlock Setsuna, you have access to a place with a "?". Setsuna ask you to put 4 donuts card to a certain order for unlocking stuff, here's the combinaison.
Password
Effect
3 4 3 1
Movie Battle
1 2 4 2
Unlock Clothes
1 4 3 2
Unlock Clothes
2 3 1 2
Unlock Clothes
3 1 3 4
Unlock Clothes
4 3 2 1
Unlock Clothes
4 4 2 1
Unlock Clothes
Setsuna
In order to unlock Setsuna, you have to make her appear as Eas in Love's Route. For this, you have to earn about 100 Clover Coin. Play the Donuts Game for this, it's the faster way in the beginning.