Touhou Kaikidan: Mystic Square

For no apparent reason, large quantities of demons and youkai begin to travel from Makai, the world of demons, to Gensokyo, swamping the land and leaving Reimu Hakurei with a lot of extermination to do. Frustrated, Reimu tracks the source of the invasion to "The Cave in Which the Door to Makai is Said to Be," which lies in the mountains behind the Hakurei Shrine. Reimu decides that it is her duty as a shrine maiden to root out the cause of this mess. Unbeknownst to her, Marisa Kirisame has learn...