You can get the first one after meeting balder. Ask about how his song went and write down the order he says. Go back to the construction area, middle taxi stop. A little to the right is the crane/backhoe puzzle. Flip the switch to raise the arm, and drop down the hole under where is was. To the right in the tunnel is a gate guarded by stone people. Ask Pesto to play Balders song to open the gate. Inside is a chest containing a soul coin and this achievement!