A Google Doodle is a special, temporary alteration of the logo on Google's homepages intended to commemorate holidays, events, achievements, and historical figures. The first Google Doodle honored the 1998 edition of the long-running annual Burning Man event in Black Rock City, Nevada, and was designed by co-founders Larry Page and Sergey Brin to notify users of their absence in case the servers crashed. Early marketing employee Susan Wojcicki then spearheaded subsequent Doodles, including an alien landing on Google and additional custom logos for major holidays. Google Doodles were designed by an outside contractor, cartoonist Ian David Marsden until 2000, when Page and Brin asked public relations officer Dennis Hwang to design a logo for Bastille Day. Since then, a team of employees called Doodlers have organized and published the Doodles.

Shusaku was a Japanese professional Go player during the 19th century. He is known for his undefeated streak of 19 games during the annual castle games; his thirty-game match with Ota Yuzo; the eponymous Shusaku opening; and his posthumous veneration as a "Go sage". Next to his teacher, Hon'inbō Shūwa, he is considered to have been the strongest player from 1847/8 to his death in 1862. He was nicknamed Invincible Shusaku because of his castle games performance.