Японский лук: история и эволюция формы и техник

the Japanese bow

Some of the bows found as burial goods in kofun (ancient tombs) during the Kofun period (300–538 CE) were decorated with gold or silver, and it is believed that they were also used in ceremonies. The length of most bows in this period ranged from , and it is thought that they were powerful enough to shoot enemies and animals at close range. In the Nara period, lacquered bows with more weather resistance and decorative features appeared. Euonymus hamiltonianus, Zelkova serrata, and Toxicodendron succedaneum, which are highly elastic wood, came to be used for making yumi, and many yumi became as long as roughly 7 [[Shaku (unit) 3 [[Cun (unit) , increasing their power and range. Since then, the structure of the bow has gradually evolved, but its length of roughly 7 shaku 3 sun has been passed down to the present day. From the end of the Heian period to the beginning of the Kamakura period (1185–1333), the (三枚打弓) was developed, and bamboo was glued not only on the front side but also on the reverse side of the yumi. In the late Kamakura period, the shape of the bow became more asymmetrical, with the upper part bent from the lower part, so that it resembled a modern bow, further increasing the range and power of the yumi. During the Kamakura period, when the samurai class came to power, kyūjutsu (archery) became more and more popular, especially the three types of mounted archery: yabusame, inuoumono, and kasagake. The (四方竹弓) was developed during the Muromachi period, and bamboo was used on the side of the bow to increase its range and power. They are traditionally made by laminating bamboo, wood and leather, using techniques which have not changed for centuries, although some archers (particularly beginners) may use a synthetic yumi. The yumi is asymmetrical; according to the All Nippon Kyudo Federation, the grip has to be positioned at about two thirds of the distance from the upper tip. The upper and lower curves also differ. Several hypotheses have been offered for this asymmetric shape. Some believe it was designed for use on a horse, where the yumi could be moved from one side of the horse to the other with ease; however, there is evidence that the asymmetrical shape predates its use on horseback. Others claim that asymmetry was needed to enable shooting from a kneeling position. Yet another explanation is the characteristics of the wood from a time before laminating techniques. In case the bow is made from a single piece of wood, its modulus of elasticity is different between the part taken from the treetop side and the other side. A lower grip balances it. The hand holding the yumi may also experience less vibration due to the grip being on a vibration node of the bow. A perfectly uniform pole has nodes at 1/4 and 3/4 of the way from the ends, or 1/2 if held taut at the ends – these positions will change significantly with shape and consistency of the bow material.

The string of a yumi, a , is traditionally made of hemp, although most modern archers will use strings made of synthetic materials such as Kevlar, which will last longer. Strings are usually not replaced until they break; this results in the yumi flexing in the direction opposite to the way it is drawn, and is considered beneficial to the health of the yumi. The nocking point on the string is built up through the application of hemp and glue to protect the string and to provide a thickness which helps hold the nock ( of the arrow, a , in place while drawing the yumi. However, it can also be made of strands of waxed bamboo.

A bamboo yumi requires careful attention. Left unattended, the yumi can warp out of shape and may eventually become unusable. The shape of a yumi will change through normal use and can be re formed when needed through manual application of pressure, through shaping blocks, or by leaving it strung or unstrung when not in use. The shape of the curves of a yumi is greatly affected by whether it is left strung or unstrung when not in use. The decision to leave a yumi strung or unstrung depends upon the current shape of the yumi. A yumi that is relatively flat when unstrung will usually be left unstrung when not in use (a yumi in this state is sometimes referred to as being 'tired'). A yumi that has excessive curvature when unstrung is typically left strung for a period of time to 'tame' the yumi. A well cared for yumi can last many generations, while the usable life of a mistreated yumi can be very short.

Yumi are featured in the Teenage Mutant Ninja Turtles franchise, used by Splinter in Teenage Mutant Ninja Turtles II: The Secret of the Ooze and the 2003 episode "Exodus, Part 1". The Foot Clan includes Foot Archers who use yumi. Leonardo, Donatello, Raphael, and Michaelangelo occasionally used yumi in the 2012 version, and yumi were also used by Karai, as shown on the flashbacks of the 2003 episode "City At War, part 3". A yumi bow was used by Murakami Gennosuke, a rhino bounty hunter in the 2003 episode "The Real World, Part 1". Power Rangers Samurai features the Blue Ranger Kevin Douglas using the Hydro Bow, which is based on a yumi bow. Yumi bows were used by samurai in Deadliest Warrior and The Last Samurai. The character Hanzo Shimada from Overwatch uses a futuristic yumi as his weapon of choice due to him abandoning the way of the sword after nearly killing his brother Genji.