My Big Sister Lives in a Fantasy World: Volume 6 by Tsuyoshi Fujitaka

As the war for the Evil God's vessels begins to escalate, an even more terrible threat comes to Seishin City. When Natsuki runs away, fearing for her life, Yuichi and his friends try to search for her. Their pursuit will lead them not only a new, deadly enemy... but a final understanding of how Yuichi came to have Soul Reader!