Issei at age 3 already knew about the supernatural as well did his parents only one that didn't know was his sister since his parents wanted her to have a normal life but Issei had different ideas he began training to get stronger to protect his loved ones he will die for them if he has to join Issei as he shakes the world with is presence it's time for Issei to defend the human race with his own hands with his friends following behind.