This particular Origami envelope is a very well known traditional Japanese Tatou. If you see the finished Origami envelope, you might think it is very complicated to fold. But if you follow the Origami video tutorial below, you will have yours folded in no time. All you need is a square sheet of paper. It is best to use Origami paper as it is easier to fold with. You will also like the color-contrasting handle feature.
A 15 cm x 15 cm / 5 7/8 in x 5 7/8in paper will result in a Tatou of 9 cm x 9 cm / 3.5 in x 3.5 in (approximate). The bigger size Origami paper of 20 cm x 20 cm / 6 in x 6 in folds into a Hexagonal Tatou the size of about 12 cm x 12 cm / 4.7 in x 4.7 in.