Z - Friendship and Nightmare

Akari, a high school student, talks to her best friend, Megumi, about her heart broken story. Suddenly their normal lives are turned up-side down— because a man attacked a fisherman tries to attack the two girls. However, they are saved by a girl covering with an eye patch. She slashes down the man = Z by her long-sword. She cuts off its legs, arms, even head, but still Z tries to attack them.