Whisper wind farm. Craft a soul lantern there. The formula is current hp to max hp. The sphinx I think? from Chiyo's gold license test--if not some other at the Taby farm will give you x3 gentle strike crystals which will aid in doing that since you won't over kill them.can someone tell me how to captuer the wild monster girls?
If you have access to rpgmaker you can look at the soul lantern item in the database, find the common event number it has assigned on the right, the go look at that and change current hp into "luck" and you'll have near 100% capture rate on monsters with them at full hp should you wanna cheat/mod it. There are many hundreds of monster girls in the game as things like imps tend to appear in 3's and you can capture them all.