Neptu is one of the things that is often considered in predicting the character of a person based on his birth weton.
Neptu is also used to predict match mate, job suitability, amount of fortune brought by a child in his family, and so on.
Well, for those of you who want to know more about Javanese neptu and how to calculate birth weton in Javanese primbon.

Neptune Java
Neptu is a value that is calculated by adding up the day value and market value.
As is well known, besides knowing days such as Sunday, Monday, Tuesday, etc. until Saturday, Javanese people know market terms like pahing, pon, wage, kliwon, and legi.
This combination of days and markets is called weton.