Shadowmen are Spirits that appear in Yomawari: Night Alone.
The Shadowmen appear as a black ghost-figure with long, bending arms. It's mouth and eyes are white. When it moves, it appears as a black cloud with some white dots.
These Spirits are invisible in the dark. They don't chase after the protagonist, but they will kill her if she gets too close.
They stay still for a while, before they suddenly move to another location. This makes their movements unpredictable, making it tricky to get by them.