Markino was one of the various skeletons of Hades, and as a skeleton, must protect a building of Hades's Empire.
Markino was sent to protect the entrance First Prison of the Meikai, where Minos protects that's prison and judges the dead people. Since the Mythological Ages, Markino protected that prison and never allowed the dead people to make some noise. But, when Seiya and Shun arrived at that prison, after Markino discover that some alive saints arrive in the Meikai, he goes screaming the notice and Lune, the current protector, kill Markino because hate noises.
Markino was the protector of Fiodor's house, and was killed by Yuzuriha when tried to stop her invasion.