I'm Standing on a Million Lives

Yotsuya Yuusuke is a ninth grader who has no friends and doesn't participate in any club activities. Suddenly one day, he and two female classmates are transported to another world where they need to work together and fight for their lives. Yotsuya was once alone and has always lived his life the way he wanted to, but now he is supposed to be a hero - how will this come about?