So long as you have made the following choices throughout the entire game, you will unlock the Luccretia ending:
Chapter 1:
- Cry.
- Say thank you.
- Answer.
- Force him to take you there.
- Grab him by his clothes and stare closer.
- Take a peek.
- Look at him.
Chapter 2:
- Say yes.
- Continue to sulk.
- Make an excuse.
- Try to remember.
- When did you become so manly?
Chapter 3:
- Say that I'm a cute girl.
- He's teasing me.
- Why get a job guarding the city?
- Why do you do it?
Chapter 4:
- Let him pat you.
- Take either choice, it does not matter.
- But...
Chapter 5:
- Ask him.
- Eat with him.
- Tell him everything.
- Tell him what you think.
- Someone could be watching.