M-ji kaikyaku M字開脚
Japanese for M-shaped open legs; M-ji kaikyaku shibari holds each leg folded and the knees apart so that the legs form the letter M, on the floor, on a chair or in suspension.
Kaikyaku (開脚) means spreading the legs apart (Jisho), and M-ji (M字) means M-shaped. SMpedia explains that M-ji kaikyaku shibari takes its name from bent, opened legs that resemble the letter M; ties that open straight legs fall under the broader kaikyaku shibari instead, and SMpedia finds the outer boundary of the term hard to draw. Shibari Study speaks of bent legs spread and tied in front of the body, and Andrea Ropes and SHIBAKU describe each ankle bound to its thigh so that the legs stay folded. SMpedia notes the tie is often done on a chair or sofa, which can bring the name isu shibari, chair tie, and calls the suspended form M-ji kaikyaku tsuri. It lists teaching material on the tie from many Japanese riggers, among them Nureki Chimuo and Naka Akira.