In the maze LV 1, the first mushroom you encounter after entering the maze, with the hero's jumping attack, you will find that the hat on it is a strange disguise. A monster on the far right will drop a blue hat and put it on the mushroom ~

The place you said should be labyrinth LV3. If you put a hat on the mushroom at LV 1, the mushroom will open the door for you ~ A treasure chest is a box in a box ~

Have fun ~