The Impenetrable Barrier

May 1842. Edo, Japan. After Honinbo Jowa's forced retirement as Meijin Godokoro in 1839, Inoue Gennan Inseki made yet another bid to prove he deserved the highest office in Japanese go. The Honinbo house lodged a government complaint that blocked his application, and a series of challenge games against Honinbo Shuwa was arranged instead. Shuwa had won the first encounter in 1840 by four points on Black, stunning Gennan into withdrawing his Meijin petition. In 1842, Gennan returned to show he could defeat Shuwa taking White. This game, played on 16, 17, and 18 May 1842 (Tenpo 13), became known as The Impenetrable Barrier: 270 moves, Black wins by six points.

A Jun-Meijin's Last Hope

Gennan was recognised by many contemporaries, including Jowa himself, as playing at Meijin strength, yet he held only 8-dan and the unofficial status of jun-Meijin. Shuwa, head of the Honinbo house in all but name, stood in his path. In this second of three 1842 games, Gennan played a skillful, patient game as White. Entering the endgame he was behind by only one point, a remarkable achievement against an opponent who would soon be acknowledged as the pre-eminent player of the day.

The Failed Invasion

Believing he needed more than a one-point deficit to make his political case, Gennan attempted an invasion in the corner, seeking life where patience might have preserved the slim loss. He misread the sequence. The invasion failed and cost five points, turning a one-point loss into a six-point defeat. Sensei's Library records that with this game Gennan realised he would never become Meijin, only forever a jun-Meijin.

Shuwa's Ascendancy

Shuwa won the third game of the series as well, by four points. Gennan abandoned his Meijin ambitions and accepted retirement at 8-dan. Shuwa's comprehensive victories established him as the strongest active player until the rise of his pupil Honinbo Shusaku. Though Shuwa never received the Meijin title officially, he is honoured as one of the Four Sages alongside Gennan, Yasui Senchi, and Honinbo Genjo.

Primary sources for this account include Sensei's Library (The Impenetrable Barrier), the CWI Amsterdam game archive (RE[B+6], 270 moves, JD Tenpo 13-5-16,17,18), Wikipedia's biography of Honinbo Shuwa, and GoBase.org match records.