The Healer who was Banished from his Party is in fact the Strongest

One of the many labyrinth cities in the world is called Martat. There lived a man named Raust, who was a healer by trade. Due to his incompetence, other adventurers rejected, used, and discarded him. Raust went through this cycle repeatedly until one day a girl named Narsena, a martial artist, appeared in front of Raust. Narsena asked Raust, who had just been kicked out of a party, "Big brother, would you like to form a party with me?"