Five years after the events of Kasumi, Kasumi was ambushed by a small army against NEW and fell into the ocean. Kasumi was later rebuilt and brought back to life by a professor who lives in an island, Professor Leonidas Charles, but she had lost her memories after the fall. Due to the amnesia, Kasumi had changed her personality to a more kinder and shy version of her old self; not soon later, she had regained parts of her memories as a killer and what she had done for NEW, and so, Kasumi had later remembered enough to wish to atone for her sins. As Kasumi once again continues her path of carnage, she now fights to undo what she has done and take back the world from its tyrant.
Kasumi - The protagonist of the game, a kunoichi who was rebuilt as a cyborg by the NEW organization after she was almost killed by her master. After her amnesia, she had began to go against NEW but is attacked by other groups as well so she works alone with Saizo to fight against NEW.
Saizo - A returning antagonist now deuteragonist and playable character for multiplayer mode. A mysterious ninja who wears a black fox mask and knows the same fighting style as Kasumi but different ninjutsu.
Nick Freeman - The charismatic leader of the NEW organization and Kasumi's former boss.
Professor Leonidas Charles - An old man who lives in a small island city and another person who saved Kasumi's life from death.
The gameplay of Kasumi 2 had not changed much from Kasumi, but this time added more attacks, ninjutsu, and improved the graphics and speed of gameplay. Unlike Kasumi, there is now a local multiplayer mode for two players to play with each other in cooperation. Like the first Kasumi, special costumes are still in the game and now costumes for Saizo has also been added.