It turns out that the costumes VIXX wore in their 'Eternity' MV and live performances are designed by the studio K. Thanks to Eliza for telling me this :D (If you miss her, she's still around and will have more posts coming up)
Who: VIXX Hongbin
Where: SBS drama "Glorious Day"
What: Shirt with Stay Real Print from A Question Of
Purchasable here.