Erina wants to train walking on a runway - of course it's going to be a human runway. She's wearing flat boots and walks all over her slave, from his legs, over his groin and chest up to his face! The boots may be flat - but the sole's hard and hurts the slave as she tries to balance on his uneven body - especially when she steps on his face and shifts his skin under the hard rubber sole. Later on the slave has to take her boots off and she tramples him in socks for a short time before she orders him to take the socks off as well. Now the trampling torture continues under her bare feet as she steps all over him again, on his chest, on his face and even on his throat - a human runway needs to endure this!
