What book and who is Ashley? The only people I can see are Sarah, Molly, dark elf chick that sells clothing enchantments which is the only thing she does and the nerd bitch, there is no one else to see and nothing else to do even the hell hole all the way to floor 25 has nothing but random monsters.
You can find 3 treasures in the dungeon - floor 11, 13 and 17 IIRC (unsure on last one).
The Book appears late in the Berserker route.
Ashley is the Berserker.
To make Ashley spawn, the protagonist (Dan/Rosa) has to be at least level 3. Go around on floor 1 until she shows up. Beat her by casting Suppression 3 times in 1 battle. She's the only encounter there, so you can't miss it. The higher your level, the faster she should show up.
Once done, bring Ashley to Julia (has to be Normal personality). Head to the streets and speak to Ashley, who'll now join you.
Reach floor 14+ of the dungeon and speak to Julia again. Tell her "Are you okay?" and then speak to her again. Depending on if you're dating Julia or not, it affects things.
If you ARE: Speak to her again.
If you're NOT: Forgive her, then head home. Speak to Ashley there and then head back to the library.
Either way, she'll tell you she need Jane's help (the ebony teacher). Agree or ask for more info. Also, at this point, a Book has appeared in the Item Shop, costing 10k Gems. Do NOT buy it if you're Rosa, but do buy it if you're Dan.
Speak to Jane in her room, then speak to Julia again. You'll fight a boss - defeat it.
If Jane is NOT your slave: speak to her in her room. Don't sign the contract, but do steal it.
If Jane IS your slave: ignore the above step.
Head to the streets. When speaking to Julia, confront her.
Now, it depends on if you have Sarah's mom or not. I advice you don't.
Swap Ashley into the party, then head to floor 15. Stay around for a few minutes (standing still is fine). I think it's like 3 minutes you gotta wait. Yes, seriously.
Head back to the room and agree to free Ashley. Julia will automatically join your party at this point, too. Congratulations, you have the heaviest (physical) hitter in the game.
One char you can easily obtain is lesbian for no reason beyond the creator fucking saying so. No, I'm not making that up. There's no plot relevance to having a lesbian character. But it's required she's lesbian. Which is fucking stupid, as she's hot. And I hate playing as Rosa.
Her name is Cass, anyway. Befriend Sarah (don't enslave her) and level her to like level 8. Speak to her in the streets (might be twice), speak to her AGAIN in Drape's room. Back her up.
Speak to Cass in the hallway and go to the first floor. Refuse the deal.
In the battle, cast Boost on her 4 times while she's at full HP. Choose any option (first time, affects how she looks though - 2nd option best option). Refuse to heal her and speak to her in the hallway until the scene starts with her kneeling down. Correct her at that point and speak to her at your place. Tell her to become your servant.
At this point, you can get the floor 13 treasure chest, which contains... milk pumps. Cass must be in your party. It changes her play with scene. Make sure to enslave Sarah after this and have her in her Tough form.
If you just wanna enslave her normally, beat her (she's easy as fuck) and cast Grapple in the scene right after the battle.
