Instructions
Go to the sixth basement floor in the Temple of the Ocean King and notice the large red door in the first room. Once you examine it, you will be asked to draw the sacred crest, though do not examine it just yet.
Open your map screen and look at the layout of the rooms on this floor. In your head, label the northwest room as "1." Directly to the east of that, label the northeast room as "2." Likewise, label the southwest room "3" and the southeast room "4." Close the map screen.
Examine the large red door to prompt the drawing of the sacred crest. The crest you need to draw is an hourglass shape and must be drawn in one full stroke. This is key to completing the puzzle. You cannot lift the stylus off the touch screen once you begin drawing.
Draw a horizontal line connecting rooms 1 and 2 on the touch screen using your stylus, and then draw a diagonal line connecting rooms 2 and 3. Draw another horizontal line connecting rooms 3 and 4, and finally draw a second diagonal line connecting rooms 4 and 1. Your drawing should be in the shape of an hourglass, and the red door will open allowing you to continue.