反り観音

反り観音 (そりかんのん)
男が仰向けに横たわった上に女がまたがって上半身を起こし腰を使うのが時雨茶臼。この状態のまま、女の体が後に反った形が「反り観音」。

Sori Kannon (Goddess Leaning Backward)
The man lies on his back and the woman straddles him face-to-face. As she humps him, her erect upper body leans back.