This is a crime-solving novel set in the Tang Dynasty.
The protagonists are White Night and Black Sun.
A black day's mischievous "stealing food" determined their future. They lived in the Tang Dynasty and would die in the Tang Dynasty.
They are Datang.
Bai Ye: taciturn, handsome, good at swordsmanship (nicknamed Bai Bingbing)
Black Sun: Lively and active, charming in appearance, good at formations (nickname is inappropriate)
Purpose: Once you take responsibility, you must be responsible to the end.