Haruto Shinohara is a high school student whose life is turned completely upside down after his mother marries Airi Shimizu’s father. Haruto and Airi dated a year ago, but a massive misunderstanding broke them apart. Now, forced to live under the same roof as stepsiblings, they have to navigate living together every single day. As if the tension at home wasn't enough, Haruto finds himself blackmailed by his classmate and neighbor, Asuka Natsume, who drags him into a fake relationship at school—all while he desperately tries not to get "executed" by Airi's dangerously possessive jealousy.