Eternal Life: Laying Low as a Fake Eunuch in the Imperial Palace

[Longevity]+ [Cultivation]+ [Great Ming]+ [schemer]+ [a protagonist with brains]

The ancient cultivator Chen Changshou practices the Reincarnation Art. With every lifetime he lives, his lifespan increases by ten thousand years. After eighty reincarnations, Chen Changshou has a lifespan of eight hundred thousand years and enters his final reincarnation.

This last reincarnation is special. For every extra day Chen Changshou lives, his lifespan increases by ten thousand years. If he manages to live to the age of eighty-one, he will be immortal for all eternity. Even if Heaven and Earth collapse and the universe is destroyed, he will still endure. All the spiritual energy accumulated over his previous eighty lives will also flow into this final life. Each day he survives, his cultivation level will rise by one stage, until he becomes the strongest in the universe after eighty-one years.

In other words, all he has to do is keep himself alive for one lifetime, and he'll live forever, invincible beneath the heavens.

In his final life, Chen Changshou is reborn in the late Ming dynasty as a young eunuch serving Empress Dowager Yi'an, Zhang Yan.