This is a cultivation world that is focused on smut. The best way to increase cultivation ranks? fuck someone that has a similar immortal path. Best way to learn a new technique? Give a blowjob or suckle on some breasts. Sure the normal ways do exist but those are for the 'Heaven's-chosen'. For the rest? They become willing sex toys to these types of individuals in exchange for quick and easy upgrades at the cost of no longer being able to follow the 'normal' cultivation path. These people are the 'disciples' or if they feel very loyal 'cauldrons'. The story is one of a reclusive master trying to navigate being 'hot stuff'.
