I wonder if that girl from the prior chapter in Girold's past life followed him along to the top of the dungeon where he was aiming and also ended up reincarnating into Luciana. It would fit rather well. He noticed something about Luciana being whoever that girl was and she noticed that he can use the same technique he did in their previous life. Could also explain why she feels more comfortable being an adventurer (and hiding herself) than royalty. It also explains why she kissed him without much hesitation this chapter.
To add to this maybe the other part of why she became an adventurer is because she was looking for him. She didn't hear about him dying while making his ascent and because she made it and reincarnated she thought he must have as well. She knew he is somewhere out there and wants to find him.
As for the succubus...uh, I have no idea where this is headed. I wonder if this succubus killed (or hid) the original Sofia and is masquerading as her now. Guess we will find out eventually.