Hans Full is a large Yo-kai, stitched together from several different parts. His skin has pink, light purple, dark purple, and grey patches. He has a large, oddly shaped mouth, with its inside being light yellow. His eyes are crossed, and red in color. He has two circle-shaped bumps on his back, and a larger one below his torso, instead of legs.
While he has no legs, he has five arms. All of his hands are purple, with four of them being right hands, and only one being a left hand. His left hand is the one at the very front.
He carries two flasks, both which have what resembles face-like wisps inside of them. From the way he keeps pulling more flasks from his mouth, he might be stuffed full of them.
Hans Full, originally called Amatera, was created by Dr. Maddiman in a secret laboratory below Nocturne Hospital, back when he was still human. Even after becoming a Yo-kai, Dr. Maddiman kept working on Amatera for decades. Since Hans Full is described as wishing for legs instead of the new arms he kept getting, he must have been awake and aware at some point during this time.
During the request "The Haunted Hospital", the player explores Nocturne Hospital alongside the Ghost Club, and eventually comes across Dr. Maddiman's secret laboratory.
Inside, the doctor has finally completed the work on Amatera, but re-names it to Hans Full, as it turned out very different than he had anticipated. He gets distracted when the player shows up along with Whisper who, despite his protests, releases the unstable Hans Full. Afraid of what might happen, Dr. Maddiman retreats, and the player has no choice but to battle the now out of control Hans Full.