Doragon Bishoppu (S02E11)

After joining up with the villagers who had left on the Journey of Hope, Yotsuya's party starts to notice that everyone is complaining of feeling tired, reminding them of what happened at Jiffon Island. When the group is attacked by monsters, a surprising figure from their past shows up and saves them. He also tells them that he's been pursuing Dragon Bishops, that their evil influence is spreading, and that he knows why all the local monsters are so much stronger than the norm. (Crunchyroll)