Step 9:Fold and unfold the left edge to the center line to creat a crease.
Step 10:This step requires two folds at the same time. First, fold the left edge to the center line. Second, open the upper layer and fold the center point of the left part of the upper layer bottom edge to the center line along the dotted line.
Step 11:Fold the top right corner of the folded part of the previous step down along the dotted line
Step 12:Fold along the dotted.
Step 13:Repeat step9 to step11 on the right part.
Step 14:Open the upper layer and fold behind.