[Comprehensive] Space-Time Postman

I have a rough idea. I'll dig a hole first and fill it in later... Li Mu inexplicably became a postman at the Space-Time Post Office. Responsible for delivering letters from people in different time and space to the recipients. The business is oriented to various time points in the second and third dimensions. Goldfinger, Sususususususu (a scumbag writer must be able to write about Su's attributes...), Ambiguous. I originally wanted to write something purely original... I'll talk about it later hahaha