When she makes you sign the contract?
It's near the end of the Berserker route.
To access it, you need to find Ashley on floor 1 (she spawns when the Protagonist is level 3+, higher level means higher odds). Cast Suppression on her 3 times in 1 battle. Bring her to Julia in the library (if Julia is your slave, she must be in Normal personality).
Head to the streets and speak to Ashley. Head to the library and speak to Julia (if the scene isn't about Ashley hating to read, head a few floors deeper into the dungeon). Once done, speak to Julia again. If this scene isn't about Ashley being sent home, head to the dungeon and head further down.
I tend to just run floor 15 which is more than plenty, for reference.
If Julia told you that Ashley is sent home, do NOT punish her. Forgive her and head home. Ashley re-joins you.
Speak to Julia AGAIN and she'll say that she needs Jane's help. Agree to help or ask for more info. Both works. Either way, speak to Jane in her classroom and she'll join you. Speak to Julia again and you'll fight the Berserker again. Defeat her. She has 1000 HP and hits very hard but lacks AoE.
Once done, speak to Jane and she'll ask you to sign a contract. Agree to do so.
If you don't agree, you can steal it to let F!Reese sign, which is another story.