The rare swords were made out of five separate pieces and heat-treated at high temperatures. The swords of the Masamune School were harder than any of the swords made before. Masamune trained a group of at least ten followers. Two of his students (Kanemitsu and Nagayoshi) were from the Bizen province. In this way, during the early 14th century, the Masamune school attracted many smiths from other schools. Kanemitsu is believed to be the one who created the Soden School, which combined Bizen and Soshu techniques. 