(edited) Because of size, M style, and front-facing portrait I thought it was Justinian I, Constantinople, but looking through a list of Byzantine coins by Sear number I think it's Maurice Tiberius, year 8, 5th officina at Constantinople.
I believe TIF is correct but this is an example of a coin that looks really nice but is missing important clues that would help with the ID. As an amateur in Byzantine, I prefer coins of Tiberius Constantine showing the cross on his crown and coins of Maurice Tiberius showing his three points (trefoil) style crown. Certainly coins without clear features can still be IDed by those in the know but amateurs like me appreciate the on flan clues when we can get them.
That coin in the first post cannot be Justinian taking into consideration that the concept of regnal year started from his 12-years period and onwards. The earlist regnal year of Justinian is thus 12. So if it is year 8 then it cannot be him. It is neither Justin II, because all Constantinople minted of Justin II are minted where he sit down with his wife. It is neither Tiberius II, because he should have consular robes in his Constantinople-minted coins. I am 99% sure it is Maurice Tiberius with Sear 494. David Sear also lists year 8 with mintplace of A, B, r, Δ and E. Here my coin with the same type with year 8 but with mintplace r:
Like the OP and @Herberto , I have a year 8 too: 34-32 mm. 13.30 grams. Maurice, struck year 8 = 589/590 Note the horseman riding right on the shield. Sear 494. I was told by a specialist studying coins of Maurice that the cross on the front of the helmet is very rare and this one is only the second known. I doubt the cross adds much, if anything, to its value.
