Images of Saitō, also known as Rigr Stafford, from the Seraph of the End series. Saitō is a second progenitor vampire with plans for the first, Shikama Dōji.
Jump SQ, October 2016 issue
WSJ, September 2016 issue
Catastrophe manga volume 9
Saitō giving money to Mika for ice cream
Yo Asami's Twitter, January 2018
Saito's description on JUMP SQ's official website