A decade ago, Ryouta Murakami and Kuroneko delved into the wilderness in pursuit of proof of extraterrestrial existence. Tragically, Kuroneko lost her life and Ryouta was gravely injured. Now a high school student, Ryouta has returned to routine life but is determined to honor his late friend by proving the existence of aliens. One fateful day, a transfer student named Neko Kuroha arrives at Ryouta's school, bearing a striking resemblance to Kuroneko and astonishing him with her supernatural capabilities. As Ryouta becomes more enamored with Neko, he is thrust into a dangerous world where scientists hunt and capture fugitive witches with magical abilities who have fled from secret research facilities. Neko is one of these escaped witches, and Ryouta must protect her and others from their merciless pursuers.