The Case Files of the Great Detective Holmes. The Koyomi School's board of directors decided to destroy the mansion, deemed too dilapidated and dangerous. This is the mansion where J lived a hundred years ago, and he intends to fight to keep it standing. In his fight, he is supported by his comrades, members of the student council, who offer him their help without even trying to find out where his attachment to this manor comes from. Alas, the plan will not go off without a hitch...