The Ruler of the Land - Vol. 91 Ch. 677

[MangaDex]

 

[frubam]

They tried to illicit sympathy for Sa Eumin, but it just doesn't work here. Maybe when he actually kicks the bucket he'll have the regrets others in the past have had for working with Sinji. Then I might feel something for him.

 

[luuylisa]

They tried to illicit sympathy for Sa Eumin, but it just doesn't work here. Maybe when he actually kicks the bucket he'll have the regrets others in the past have had for working with Sinji. Then I might feel something for him.

Or maybe the author just simply provides background for 1 of many mysterious Sinji warriors, before giving them death
As for regrets, I don't think he will. I have a feeling that he was raised in Sinji since birth, thus know nothing of the outside world