It begins with Arthur working as farmer,wishing to be a Knight like his father. He goes to the market where he notice that the Knights are preparing for the gauntlet. Some of them fails until Arthur steps up and prepares to compete. After succeeding it,Princess Prin Prin was impressed.
Arthur was about to be name Knight,the winged demons captures Prin Prin. Arthur begun traveling to retrieve her along with Lance. A the Demon Realm,Astaroth,former ruler of Makai,wants to marry Prin Prin so they rule the world and take back what was rightfully his. He suddenly learned that Arthur & Lance are coming here. So he sent Firebrand,the Gargoyle,& Unicorn,the Cyclops,to intercept them.
The two knights fought against them. Arthur manage to blind Unicorn and tripped him with the ropes,causing him to fall to his death. After Lance gets knocked unconscious by Firebrand,Arthur defeats him. Arthur goes to the Demon Realm to free Prin Prin,but was confronted by Astaroth.
The two fought eachother until Arthur gets overpowered. Astaroth tries to crush him,But Lance threw the spear at the demon's back,allowing Arthur to stabs him in the heart,killing him. The people hails Arthur as a hero and received a kiss from Prin Prin.