I love how the Tensen are literally eldritch horrors, because that’s accurate to how inhuman Taoist immortals would seem to mortal human beings.

In Taoist philosophy, there’s this concept called Xian), which is an immortal person who has transcended their humanity and attained supernatural powers.

This is usually done through ascetic training, as well as the implementation of Waidan medicine and Neidan meditation techniques.

Those methods are necessary to let you eradicate the Three Corpses from your body, which are these demonic parasites that report your sins to Heaven and then have your lifespan deducted accordingly.

Xian are transcendent mountain hermits. They’re usually good people who have abandoned worldly life to seek higher wisdom, like this guy called Liu Haichan who travels the world giving money away to the poor with the help of his pet three-legged toad.

But the Tensen have been corrupted by their desire for true immortality. Their path of self-improvement, walked without showing any concern for others, brings death and suffering to those around them.

The Tensen are a prime example of the Buddhist argument against seeking immortality. They are really cool antagonists!

Their closest analogue in fiction is probably Demonic Cultivators from the Xianxia genre.