Virtus

Virtus (ヴィルトゥス) is a manga written by Gibbon and illustrated by Hideo Shinanogawa. It was serialized in Big Comic Spirits.

Plot
Year 185, Commode emperor, cruel and thirst for blood, led Rome to its ruin. Instead of governing he prefers fighting in the arena. For, Marcia, his concubine, Rome has lost what has made its pride: Virtus

Desperate, she asks a witch for help. With magic, she casts a group of prisoners from the modern japanese era.