The fun part is the folding, inspired by Japanese furoshiki and bukuro.
If you like you can leave your bag flat, or you can turn it inside out and fold the bottom corners to form a flat bottom and fasten the flaps with a few strong stitches.
You don’t have to crochet this - you could also use a felted, knitted rectangle or a length of fabric.
Make it small and use it as an evening purse or make it huge and use it for shopping.
The name Masa Bag is inspired by a Canarian/Japanese sushi place in Las Palmas that I visited just after buying the yarn. My bag is Spanish-Japanese just like Hideo the sushi cook!