Mokushiroku no Yonkishi - Vol. 2 Ch. 7 - The Demon at the Valley of Tree Spirits

[MangaDex]

 

[Artyk04]

Well we have a potential Knight of the Apocalypse

 

[Erangel]

At first I thought it may be King and Diane 'son but now I'm starting to think it might be Zeldris son because of the blood near the mouth and them calling him a demon

 

[dende]

The blood is probably from biting his lip