Teppō 鉄砲
Japanese for gun or rifle; teppō shibari is an asymmetric arm tie with one arm reaching behind the head or shoulder and the other behind the back, like a rifle carried on the back.
Teppō (鉄砲) is the Japanese word for a firearm, usually a rifle. In rope, teppō shibari (鉄砲縛り) is an asymmetric arm tie. Japanese Wikipedia describes one arm passing over the shoulder and the other coming around from the side to meet it on the back, and explains the name by the resemblance to a person carrying a rifle on the back. Shibari Study gives the English name rifle tie, with one arm bound behind the head and the other around the back, and Rope365 describes one elbow pointing up while the other arm stays behind the back.