From a start door, descend a ladder near a door.
There is a trap hole on your left, so drop a wooden box next to a liquor into a hole.
Keep going to the left.
You can see several trap holes on your left.
Taking care of liquors and appearing wooden boxes, drop a wooden box into a hole and get over them.
Get a key beyond these holes.
After you got a key, go down and down to the lower left.
You will reach a goal door soon.