Right after you open your first treasure chest on Mt. Mabinogio Ruins. Sorey will comment something about it, make sure you check it.
After the first monolith, continue until you find 2nd save point on this ruins. It’s on the big square room.
On the same room where you take the “event” treasure chest (Mikleo takes the glove from you); near the stark mark.
After getting out from the Mt. Mabinogio Ruins, head north a little bit to find the monolith.
On the east corner of Elysia home of Seraphim.
On the south part of the Elysia home of Seraphim (near the save point).