It is said that a coffin on which Shingen's Kaimyo (posthumous Buddhist names) and the year and month of his death were inscribed was discovered in 1779 when the excavation was conducted, and it is believed that Shingen's remains were preserved after cremating his body just after his death.
円光院では安永8年（1779年）に甲府代官により発掘が行われて信玄の戒名と年月の銘文がある棺が発見されたと言われ、死の直後に火葬して遺骸を保管していたと考えられている。