The year is 1575 in feudal Japan. Oda Nobunaga's (Kippei Shiina) forces defeat Takeda Katsuyori, when Nagashino Castle was besieged during the Battle of Nagashino. The next year Oda Nobunada decides to build a lavish new castle symbolizing his unification of various factions. The castle named Azuchi Castle will be built near water and high enough to be seen from the capital city of Kyoto. Director Mitsutoshi Tanaka's adaptation of Kenichi Yamamoto's novel of the same name received the 33rd Japan Academy Film Prize for Excellent Art Direction.

High school girls Kotori Morino, Azumi Hattori, and Madoka Hino secretly fight against the evil Satanzola society as the Sailor Cats, messengers of justice. One day, while being attacked by assassins trying to steal an inherited hand mirror, the three are sucked into a mysterious black hole and wake up in the Azuchi-Momoyama period.

Following the events of the previous movie, Kotori and her friends return to the present only to discover that Japan's history has changed. To restore the timeline, the Sailor Cats must travel back in time again to protect the life of Ieyasu while battling the Kouga army.

A reporter is sent through time and space to document the lives of Japanese people at various times in history. This time, he is sent to unwrap the mystery of Azuchi castle which was built by Oda Nobunaga, one of the most famous shogun of all times, and lost within merely three years after its completion.