Sacred Mark. Those who have this mark possess a special power. The protagonist, Narumi, is a teacher who bears a strange mark on his right shoulder. It appeared when he was a child and various unfortunate incidents have occurred since then. Despite it being a nuisance to him, it has a significant meaning in the world. It is said people who have such a mark have the ability to train "knights". Because of the mark, Narumi is involved in a battle between two groups, the Big Angel Religious Community (BARC) and Sacred Mark Knight Community (SMKC). Now a SMKC member, his mission is to train three girls to become powerful knights. A battle that has lasted over 1,000 years now enters a new phase...

[Edited from ErogeShop]