The Spring of 2094 AD. A young girl whose calling is assassination, Hashibami Yuki, is witnessed by a young middle school boy at the scene of a crime.

Supressing misgivings about erasing a young middle-schoolboy, Yuki’s superior abilities cannot compete at all. The name of the mysterious boy is Shiba Tatsuya.

If the opponent was a normal boy,

If the opponent was not a magician,

If the opponent was not Shiba Tatsuya—

An "irregular" boy and an "assassin" girl. The meeting of these two will alter fate and bring misfortune.