Edo Castle is surrounded by a disturbing atmosphere. A general without a child fell seriously ill. Amid the battle for succession, the shogun calls for Amari Bizen no Kami and summons his younger brother Yukichiyo, a man that looks exactly like Unokichi.
However, someone immediately begins attempting to assassinate Yukichiyo who manages to escape and disappear. Amari Bizen, seeking to keep Yukichiyo safe, makes him the fake Unokichi and makes Unokichi the fake Yukichiyo.
~~ Adapted from a novel by Ban Daisuke.