Blade of Destiny: The Rebirth of the Phantom

issei is mistreated by rias peerage because they think it will make him stronger, it make him mental breakdown and almost comitted suicide because sona and tsubaki stop him, they tell that he is strong, issei is hug both sona and tsubaki to cry, sona then tell him that she know a person who can see issei potential make issei shocked, tsubaki tell is yoshimitsu, a leader of the manji clan, with the strong sense of justice and have a eclectic mix of swordmanship and ninjusu, sona suggest that he need to train with yoshimitsu, and sirzech came with a nod said that yoshimitsu contact to sirzech and say that he want to train issei under his wing, he agree as he is exited and prepare but peerage stop him because they denied, when rias try to reach issei, he kick in rias stomach and sona and tsubaki attack rias with the slap on rias face, issei prepare stuff to go to yoshimitsu place and vow that he will protect the kuoh by his own way after he done his training