揚羽本手 (あげはほんて)

揚羽本手 (あげはほんて)
男の腰や胴に絡んだ女の脚の動く様を蝶に例えている。

Ageha Honte (Butterfly)
The woman's legs, wrapped around the man's body, go up and down as they hump on, which look like fluttering butterfly wings.