C³ - CubexCursedxCurious

One day, Yachi Haruaki receives a big black cube from his father, who works overseas. Overnight, the cube morphs into Fear, a tsundere loli who has turned up to remove the curse placed on her through accumulating negative emotions. At night, Haruaki encounters her stealing rice crackers, and allows her to stay at his place, much to the horror of Konoha, Haruaki's childhood friend.

Haruaki arranges for Fear to join his school, where to his surprise, she ends up well-liked and happy. After her first day, she goes home with Haruaki and Konoha only to be attacked by a strange woman trying to kill the "Fear in Cube".

Using her power to the full to beat Peavey, Fear calls up various torture devices using her cube to attack her, including a massive guillotine that cuts off her left arm completely. Still in a crazed state, Fear attacks Haruaki before running away and trying to commit suicide, but Haruaki goes after her.

Haruaki and Fear are faced with a life-and-death decision when Mummymaker pays them a visit.

The final battle between the maniacal Worse Hunter Peavey Barowoi and Fear happens just as Yachi and Konoha are sidelined! Making matters worse, Kirika is a defenseless hostage... or is she?

After returning to school, Fear and Haruaki are contacted by the principal once again, who tells them that a certain student, Shiraho hasn’t been turning up. Coincidentally, Shiraho was recently sent a box containing a cursed tool, and the doll, Sovereignty escapes by assuming human form. Haruaki and Fear try to track the doll down.