The Ranking Book is a book that is half as tall as younger Futa and an item that he always carries around. He uses it to write down lists of rankings he has made. According to him, he would forget the information he received from the "Ranking Planet" if he didn't write it down.
It is said that whoever possesses the Ranking Book could control the entire Mafia world due to the massive amount of information about all of the Familigias written in it. In the future, Futa appears to have traded in his Ranking Book for a briefcase.