My Spirit Pact Is with the King of Hell?

Beneath the stars, on a wasteland,

there stands a manor,

at the very heart of the scorched earth.

Its soil is the richest around, yet no one dares go near.

Within that manor,

there is a legend,

there is a demon.

One followed a whim and made a [Promise], becoming a Daoist sage a thousand autumns later.

One held to a childhood [Pact], falling into demonic darkness ten thousand years later.

And so, a library rose from the ruins, recording the past, the present, and the future.

Then,

a [Contract] will reveal the truth behind it all.