Assassinations and Dokis Time

Hanamori Aretha, Nagisa's cousin, was coming back to Japan from overseas and transferring into 3-E. Coincidentally, Akabane Karma, ended his suspension on the same day she arrived in 3-E. When the duo forged a competitive rivalry between them, the class of 3-E and Korosensei never experienced a dull moment again. With both of them specializing in different assassination skills yet having about the same amounts of talent and potential, would they continue their rivalry, or work to be an invincible duo?