Because of Louis' intended purpose to be sold as livestock in the Black Market, he has a permanent "4" tattooed on the underside of his right foot.

During Legoshi's fight with Riz, Louis offers Legoshi his right foot as a source of energy. After losing his foot, his adoptive father Ogma pays for a prosthetic so he can walk properly again.

So Louis was sitting on the bench and he looked down at his feet because he does have a prosthetic leg on the right and his left leg was still there.