Koshu Inden is a leather craft tradition in Kofu, Yamanashi Prefecture. The key characteristic of this craft form is that artisans use deerskin leather and apply intricate patterns with lacquer. Traditional craftsmen smoke the pieces with straw smoke and pine resin to give them a unique color. These techniques are used to make a variety of products such as bags, wallets, and accessory cases, and during the Sengoku period, koshu inden techniques were also used in making military equipment. The leather is soft and light, the use of lacquer makes it strong and long-lasting, and the more it is used, the more lustrous it becomes.