The 第一道屏障的钥匙 is an Important Item in 异度神剑X. It must be obtained along with the Second and 第三道屏障的钥匙s to lower a forcefield during 歼灭蒂法尼亚. It is dropped by the 「守卫」米尔萨德 at the entrance to the southeast room of the 格罗斯洞窟基地 in 黑钢大陆.
Map showing the location (1) of the 「守卫」米尔萨德 with the 第一道屏障的钥匙
