Awkward math whiz Kenji jumps at the chance to spend summer with his crush Natsuki, only to find himself posing as her fiancé in front of her entire extended family. As if that wasn't stressful enough, his tinkering with a mysterious equation accidentally unleashes chaos on OZ, a virtual world deeply intertwined with reality. With the world on the line, Kenji and Natsuki's loud and lovable family must band together to set things right.