Hiroshi Matsushima woke up in a dimly lit underground space.
He opened his eyes, propped up his body, and looked around. This place seemed to be a ruin of collapsed walls. It must have been a magnificent place before the collapse which seemed to have occurred a long time ago. There was even a slight metallic sheen to some fungal stains on the ground.
"Where is this? Zero?" Hiroshi Matsushima asked.
Shortly after entering the underground area, he had fallen into a coma. At the last moment of his consciousness, he had relinquished all control of his prosthetic body to TX-0, allowing it to operate in his stead.
This wasn't even "loaning out the brain." His own mind was comatose from brain damage, and Zero was completely relying on its artificial intelligence to control the prosthetic body.
