Step 1:
Prefold in half over these four lines.

Step 6:
Press the edges indicated by the arrows downwards.

Step 5:
Fold the end at the bottom of the arrow upwards by making a valley-fold over the yellow line.

Step 2:
First, make 2 valley-folds at the bottom-right. Then make 2 mountain-folds in the middle. And make 2 valley-folds at the top-left.

Step 4:
Unfold both folds.

Step 3:
Fold over these two lines

Step 10:
Make an inside reverse fold over these lines by pulling the end indicated by the arrow to the inside of the model. The short line on the left is on the same place as the folding line on the right in the picture of step 9.
Repeat steps 9 and 10 on the end at the left.

Step 8:
Fold the 2 ends upwards by making a valley-fold over these 2 lines.

Step 9:
First, prefold over the line on the left (fold the end indicated by the arrow on the right to the place indicated by the arrow on the left). Then prefold over the line at the right (fold the end at the right to the first prefolded line)

Step 7:
Repeat steps 3 to 6 on the backside.

Step 16:
Make an inside reverse fold over these lines by pulling the end indicated by the arrow to the inside of the model.

Step 15:
First, make the valley-fold on the flap below. Then make the mountain-fold over the upper flap. Use the folding line on the right in the picture of step 13 as guidance. Press/twist the tail firmly flat between your fingers.

Step 12:
Fold the model in half.

Step 11:
Fold the large flap downwards. Make the same fold on the backside of the model.

Step 14:
Pull the flap indicated by the arrow out of the model.

Step 13:
Prefold over the line at the left by folding the end at the right to the folding line indicated by the arrow on the left. Then prefold over the line at the right by folding the end at the right to the first prefolded line.

Step 19:
Make a valley-fold over this line, use the corner at the arrow as guidance to make this fold.
Repeat steps 17 to 19 on the other side of the model.

Step 18:
Mountain-fold over this line.

Step 17:
Make a valley-fold over this line, use the corner at the arrow as guidance to make this fold.