I, the Sect's Holy Son, Have Checked In at the Forbidden Grounds for a Hundred Years!

He transmigrated to a fantasy world, became a sealed Saint Child, and was locked away in the sect's forbidden grounds. Little did he know that this would activate a sign-in System. "Ding! Congratulations, Host. Successful sign-in at the forbidden grounds. Reward: a thousand-year-old spirit pill." "Ding! Congratulations, Host. Successful sign-in at the scripture library. Reward: a Heaven-tier magical treasure." "Ding! Congratulations, Host. Successful sign-in at the sect's dragon vein. Reward: an astonishing cultivation technique." ... He kept quietly checking in, until one day, when the peerless sect faced utter destruction, he finally drew his sword!