Sylvie's story is available after you cleared Silvia's story. You can skip the prologue. The story will loop itself unless you get the true ending. There are three bad endings that can loop you.

To get Sylvie's ending you need to answer (all the correct choices):

• Ask to go together
• Do you watch anime?
• That song sounds familiar
• Dear Butterflies (Come on, it's the game's title! Get this wrong and you will get bad ending))
• I like it

(If your points are not enough, you will get the bad end 1 here. The story will start over.)

• Ask
• Surprisingly fun

(If your points are not enough, you will get the bad end 2 here. The story will start over.)

• Ask Caladrius/Do nothing 

(If you choose 'Look anyway', you will get the bad end 3 and the story will start over. If you want more dialogues choose 'Ask Caladrius'.)

Once you passed this, you will get to see the ending.