Back at the Shrine of Mysteries, talk to the spirit and choose to look at the blue pedestals. Upon taking a closer look at the northwestern pedestal, you will see that only one fragment is missing, which you already have, so put it in to be transported to a new land. This is a very small island, with not much besides a little village on it. Head inside and you will see a bunch of stone statues, that taking a closer look will reveal them to be actual people turned to stone.
Just outside of the northwestern house are two pots, one of which contains 10 gold coins . The house on the eastern side has a Leather Hat inside one of the cupboards, and the big house in the north has a set of Plain Clothes in one of the cupboards. That’s all you can find for now and you might have seen an old man in the north of the village, who is actually normal, so go and talk to him, being extra careful of the poisoned water.
The village is cursed somehow and the old man gives you a bottle of angel’s tears, while also warning you about night in the village. So, go to the inn and check out the bed to go to sleep, with the Hero waking up to explore on his own. As you walk around the place, you might notice that one of the stoned people is glowing, so go investigate it to learn some of what happened. Unfortunately, the statue crumbles, so check out the eastern side of the village to find two more statues that are glowing.
Make sure you pay attention to the backstory with the little girl, as it will give you a hint on what to do next. The old man from before is just east of the big house, so talk to him and go to the one house which was blocked by the man in front of it. His statue broke, so you can now go inside, checking out the one bookshelf to find the kid’s note that was mentioned in the little girl’s past. It talks about the entrance to the secret base, which is close to the house you’re currently inside of now.
It’s a little hard to explain, but you’re looking for the lone tree just southwest of the house with the note. If you’ve found the tree, then the secret entrance is just north of that tree, so just spam the A button around until you get a confirmation from the tree. You can’t go inside yet, so head back to the inn and rest, then take the party to talk with the old man by the well again. After you do this, you can go to the spot with the hidden staircase to go underground.
At some point, there will be a split path. Take the shorter one with the stairs to come to a small room with a bunch of pots to break, netting you 5 gold coins and a Medicinal Herb . The other path will lead to a ladder, letting you get on top of that pillar you saw in the village and release the angel’s tears. This will also bring out of hiding the little boy from the flashbacks, so exit the underground area and speak to him. He will end up temporarily joining your party so you can help him search for the other villagers.
Before you set off on "searching" for them, go down the stairs he came out of and pick up the Yellow Fragment on the floor. Back above ground, find the old man by the well and speak with him, who ends up recognizing little Felix. That’s about all you can do in Regenstein, so whenever you gain control of your party again, exit and take the teleporter back to the Shrine of Mysteries.