Trapped succubus

When gaining access to Cassie's safehouse, the player may find a chest on the second floor, which contains a key.

Abandoned park
In the western part of the Abandoned Town, there's the closed gate; now, it can be opened, unlocking the entrance to the Forest Park. The part of park available for exploration is highly limited at first. In the north-eastern part of the park available to you, there's a trapped succubus you can interact with; talk to her.

Freeing succubus
After accepting the quest, an opportunity to cross on the other side opens up, by using the tree to make a makeshift bridge. After that, the only thing required to finish this mini-quest is to go across (your target would be right above the location with trapped succubus) until you reach the cave where some fairies got succubus's tail trapped and now tortures her. You just need to shoo them away. For additional scene later on, you may also tease her some more by yourself.

After rescuing her, just move back and talk with succubus (who would introduce herself as Rinny) again. After finishing the quest, you unlocks new zone – Transylvania.

Visiting Rinny
When arriving to Transylvania, the player would see that all buildings are locked tight, preventing the access; the gates to a graveyard are locked too. However, in the south-western part of the town, there's a rather suspicious dead-end; it's a hidden passage to Succubus Tower which can be unlocked by going closer enough (having high enough Senses stat would mark it on the map preemptively).

Behind it, there's an abyss, but the guard, when talked to, would extend the bridge, allowing Lust Doll to proceed. Inside the tower, they would meet Rinny; she would ask wether they're here just to meet her, but the answer has no effect on the outcome.

One the player talks to Rinny, they may proceed to the next quest whenever they're ready.