User blog comment:Crimson and Darkness/Volume 25 discussion blog/@comment-2402:3A80:D6C:B922:FB5B:B600:876:9167-20180322153522/@comment-2601:8C:601:5692:3C7E:1CB6:535F:4949-20180330222942

It's Kouki Samejima, and the two are members of Tobio's "Slashdog" Team (his squad(?) in Grigori, which becomes the basis for his Azazel Cup team) who possess Sacred Gears that seal two of the "Four Fiends (Sìxiōng 四凶)" of Chinese mythology. The other two possessors are revealed in Slashdog Volume 2 with one {most likely} joining the team.