You and she went to the same high school. She was in the kendo club. You and she were close and spent quite a long time together, and you shared a dorm room. Then one day... a zombie virus spread, and half of the students in the school turned into zombies. Your school must have had at least 5,000 students. So there were about 2,500 zombies. She killed the zombies and gathered the students who weren't infected. Since she was in the kendo club, she fought with kendo, and she was very strong.