An Assassin living as Crown Prince in different world

Leonidas van Evangelist is the crown prince of the Evandel Kingdom.Due to various circumstances, inside his body also dwell 2 different souls.An assassin from Earth, Kanzaki Ayanokouji and the strongest Demon Lord, Arcadia.However Kanzaki get the biggest dominance of Leonidas's body.With 2 powerful soul, the crown prince will show extraordinary talent when it come to combat. Note : I don't own the picture I am sorry for a quite bad grammar