Shibukawa Harumi (渋川春海)

Harumi SHIBUKAWA (his name can also be read as Shunkai SHIBUKAWA) (November 1639-November 1, 1715) was an astronomer, go player and Shintoist. His childhood name was Rokuzo, his adult names were Harumi (or Shunkai), Junsei, Harumi (written with different characters); he was also known as Sukezaemon, used the pen-names Shinro and Tsutsuchi and was known posthumously as Doshureisha. He was the creator of the Jokyo Calendar. He changed his last name from YASUI (written 安井) to YASUI (written 保井), and lastly to SHIBUKAWA (written 渋川).

He was born in Kyoto, the son of Santetsu YASUI, the first head of the Yasui family and official professional go player under the Edo bakufu (Japanese feudal government headed by a shogun). He became the second generation Santetsu YASUI upon the death of his father in 1652, but wrote the name YASUI with the characters '保井' because the family's adopted son, Sanchi YASUI (written 安井), had become the head of the family. He took part in the oshirogo, or Castle Games (a series of games played in the Shogun's castle) for the first time when he was 17, beating Doetsu HONINBO by kuroban four moku (four points as a black stone player).

He learned mathematics and calendar study from Masaoki IKEDA, astronomy from Gentei OKANOI, Suika Shinto (fusion of Shinto with Chinese elements, esp. neo-Confucianism) from Ansai YAMAZAKI, and Tsuchimikado Shinto (Shinto of Tsuchimikado school) from Yasutomi TSUCHIMIKADO. Japan at that time used the Senmyo Calendar, which had been imported from Tang China in 862 and had acquired significant errors. He therefore created the Yamato Calendar by modifying the Chinese Juji Calendar for use in Japan.
Harumi asked the imperial court to use the Yamato Calendar but Yoshisada TANI (he was also known as Issai and Sansuke and was the son of Jichu TANI), a vassal of the Kyoto shoshidai (governor) Masamichi INABA,
claimed Harumi's calendar making was unsound and issued an imperial edict ordering the use of a slightly revised version of the Daito Calendar. Harumi later convinced Yasutomi TSUCHIMIKADO, the top authority in calendar studies, to agree to the use of Yamato Calendar and, on his third submission, it was finally accepted as the Jokyo Calendar by the imperial court. It was the first calendar to be developed in Japan. As a result, on January 5, 1685, he was appointed the Shogunate's first official astronomer and retired as a professional go player. From then on, the role of astronomer became hereditary.

Astronomy influenced the opening moves of go, with the first place to put stones judged to be the tengen (in the center of the go board), inspired by the idea of the taikyoku (North Star).
In the oshirogo of October 17, 1670 against Dosaku HONINBO, he placed the stone first on the tengen and bragged, 'If I lose in this game, I will never place my stone on tengen again in my lifetime.'
However, he lost by nine moku during this match and, from that day, no longer played first from tengen.

He changed his name to SHIBUKAWA in 1702. This was because his ancestors ruled Shibukawa-gun, Kawachi Province, but moved to Yasui-go, Harima Province and then returned to the old estate at Shibukawa.
His written works were 'Nihon Choreki,' 'Sanrekiko,' and 'Jokyo-reki sho.'