Kurushima Kinai (久留島 喜内, died January 9, 1757),[1] also known as Kurushima Yoshita[2] and Kurushima Yoshihiro (久留島 義太),[3] was a Japanese mathematician in the Edo period.
[4] The Japanese board game of shogi attracted Kurushima's interest; and he was recognized in his own time as a master player.
[5] Among shogi players, he continues today to be well known for seven "puzzle ring" gambits with subsequent sequenced maneuvers—including the "silver puzzle ring.
His mathematical gift was highly esteemed.
[7] Kurushima, like most of his contemporaries, was very interested in the mathematical problems involved in "magic squares.