The Red Dragon's Older Brother

Issei has a older brother granted Issei's older brother has never been there for Issei as he left when Issei was very young see Issei's brother is only five years older than Issei but he was incredibly intelligent and about two years after Issei was born his brother left to study abroad as his parents though sadden accepted this and were very proud of him however Issei was now a second year in highschool and hasn't heard of his brother since then however one day about a week after Issei defeated Riser his parents get an invitation to a wedding, but not just any wedding but their older child's wedding as they were overjoyed and now Issei must face the person he despises most the one who left without a word and was never there for him his brother