User blog comment:B214/Volume 22 spoilers/@comment-95.90.227.198-20170206220903/@comment-24941352-20170209092148

Let me guess your so fixed on Issei being the Son of Shiva or a Descendant from him, is because you read MknR. Since many people compare Tatsuya with Shiva, because of his powers.

(And i would count Tatsuya as a OP character from the very beginning, he can destroy everything and restore everything in a time span from 24 hours. He can even restore himself, if his body should be damaged.)