Usagi 兎
Japanese for rabbit; usagi shibari, the bunny tie, binds the arms with the hands behind the head and the elbows raised, a shape compared to a rabbit's ears.
Usagi (兎) means rabbit or hare (Jisho). Shibari Study defines usagi shibari (兎縛り) as the arms bound behind the head and gives the English name bunny tie. Andrea Ropes describes the arms folded over the shoulders and behind the head to suggest a rabbit’s two ears, and counts it as one of two forms of wakizarashi, the exposed-armpit position. Shibari Mallorca lists usagi-zuri, a suspension with both elbows above the head. Japanese sources describe the arm position under other names: Japanese Wikipedia has 後頭両手縛り, both hands bound together behind the head, and SMpedia’s entry 後頭後手縛り gives aliases such as wakizarashi and banzai shibari but not usagi. Rope365 calls the same position bunny ears.