Sukai Wōku (解離法 《スカイ・ウォーク》)
When Shiro discovers that a game of reversi is causing Sora to fade from existence, she jumps into the match to save her brother.
They are both NEETs and Hikikomoris… but on the internet, the genius gamer siblings Sora and Shiro are known as the undefeatable “__” (blank). Sora and Shiro’s talents and skills are so abnormally good they are considered as urban legend. One day a young boy Teto appears before them, claiming to be “One’s Lord”.