Mythril Mines

Basement Level 1: From the entrance, head left to defeat a Black Blade mercenary and rescue 2 boys. Open the chest for an X-Potion. Return to the entrance and go down at the junction. At the next split, go right to find a Black Blade and 2 more boys. Return and go left, navigating the myriad of paths. Continue left to find another Black Blade and 2 boys. Go to the bottom-left corner for a chest with an Earth Drum. Head to the bottom-right corner to find a Black Axefighter and 2 more boys. You should have rescued 9 boys. Take the nearby stairs down.

Basement Level 2: Follow the tunnels clockwise. At the first junction, take the higher path. At the next junction, head left to find a Black Blade and 2 boys. Continue up to find a blue locked chest. At the splintered crossroad, head down to find a Black Blade and 2 boys. Travel right from the crossroad to a junction, then go down to another junction. To the left is a chest with 1000 pg. Continue down to find a Black Blade and 2 boys. Back at the first junction after the crossroad, head right to a third junction. Go up to find a Black Blade and 2 boys, plus a chest with a Turbo Ether. Follow the tunnels all the way down, then turn right at the junction to find a Black Blade and the last 2 boys.

Exit and Next Objective: With all canary boys rescued, exit the mines using a Teleport Stone or by following the tunnel left to the stairs. Upon exiting, you learn Egil, the 20th boy, was taken by the Swordbearer. Your next objective is to march to the Swordbearer's HQ to rescue Egil.