Having recently lost his mother, middle schooler Tarou Hanaukyou is now supposed to go live with his grandfather in Tokyo. When the boy arrives at his grandfather's supposed place of residence, however, he is met with a surprise—the house turns out to be a massive mansion tended to by hundreds of maids!

After a warm welcome, the head maid Mariel presents Tarou with a short video message from his grandfather, insisting that his grandson inherit his whole fortune. Though unsure about the situation, Tarou begins settling into his new life, in which the maids of the mansion will do anything for their young master.