Touru lost his parents at a very young age and had been living with his grandfather ever since.
But while his grandfather is recovering from a surgery, he suddenly opens up to his grandson that he will inherit his entire fortune when he dies.

Now his relatives who weren't closed with him, started pushing themselves so they can be his guardian.

"Organize that family meeting of yours on Saturday the 10th, it might just be your lucky day" said by Tsukitani-sensei his university professor. Touru has no choice but to believe in those words.