A young bride, Mary Yamada, is about to marry her groom Shoji Harudo at their wedding. A false god, named Saint, appears and imprisons many humans (including her groom) to make room for new ones (from different universe) that are being transported to Mary's world. When Mary Yamada almost get caught by Saint, a magical sword appears out of him, and Mary uses it to free the wedding attendants, while also jointed by the likes of Jason, Hannah, Jack, and others from their respective universes.

Realizing that the sword (known as the God's Steel) is the key to bring the other heroes and their friends back to their own universes, Mary must make her way to a newly created sky castle Saint has created, and defeat him with no mercy while also freeing the imprisoned humans, including Shoji.