No game no life

This give that two people Shiro the youngest and Sora the oldest. There were in there room playing video games for five days after playing Shiro got a message from someone they don't know asking if they want to be reborn to a new world with out a doubt they said yes and a game of chess came out the computer and Sora said that Shiro to play they never loses to anyone but themselves they call them selves blank.