Japanese swords played a large part in Japan's history during the feudal era all the way up to the Meiji restoration in the 1860s. Origami's history traces back to the sixth century when it was brought to Japan by Chinese Buddhist monks. Samurai swords were quite long, while ninja swords were made smaller by necessity. Unlike a steel sword, which could take weeks to create, making your own Japanese origami sword only requires an hour and a few sheets of paper.
Cut two pieces of origami or construction paper to 20 by 20 cm (8 by 8 inches). Lay them flat on the table. Put one sheet aside for later.
Fold a horizontal crease exactly halfway between the top and bottom edges of the paper, lining up the edges as you fold. Keep the edges together, then fold the paper twice more in the same fashion. Put it aside.
Cut a sheet of paper to 20 by 10 cm (8 by 4 inches). Put it on the table with the smaller side facing you. Starting from the bottom, make eight 2.5 cm (1 inch) folds to create a fan-like effect, creating horizontal creases all the way across the paper each time. Put it next to the first sheet of paper.
Put your last 20 by 20 cm (8 by 8 inch) sheet of paper on the table. Turn up the lower right-hand edge until it touches the upper left-hand edge. Run your finger along the crease, then pull the lower right corner down again. Bring the same corner up to the crease you just created, and crease it again. Do the same with the upper left-hand corner, bringing it to meet the crease and folding it. Both points should now face the crease.
Slip the first sheet of paper underneath the right-hand fold you just created. Fold it backward so it covers that fold and forms the sword handle.
Bring the upper portion of the second sheet downwards, crossing from the right to the edge of the left so it slightly covers the handle. Do the same with the lower portion in mirror-image fashion so the handle is covered. The blade might look a little rectangular right now, so fold the blade portion back a little to create a tapered look.
Fold the 20 by 10 cm (8 by 4 inch) sheet of paper around the sword handle to lock the other two sheets in place.
Never try hitting anyone with the sword, even in jest. Sharp objects, even those made from paper, can end up hurting someone's eye. Playing safely will prevent a trip to hospital.