Tokyo faces unprecedented danger when a mysterious creature, dubbed Monster M, rises from Tokyo Bay and makes its way into the heart of the city. Three sisters, Minami, Ushio, and Yuuhi, share some connection with this monster. Ranga, the true name of the monster, makes his way to the sisters only to face the military might of Japan. Minami, Ushio, and Yuuhi find their lives forever changed as Ranga seems ready to allow nothing to prevent him from reaching them. What ties does this monster have with the girl\'s long lost brother, and who is the mysterious boy who now lives with them?