Darenidemo Dekiru Kage Kara Tasukeru Mao Tobatsu

Summary from Comic Walker :
Holy Brave, Toudou Naotsugu was summoned from another world to defeat the Demon Lord. Priest Ares was ordered to provide support for the the hero while hiding his true level, however… This is a story of High Priest Ares guiding the Holy Brave on their path to become a Hero.