Shokugyou Mushoku no Ore ga Boukensha wo Mezasu Wake.

Shokugyou Mushoku no Ore ga Boukensha wo Mezasu Wake. (職業無職の俺が冒険者を目指すワケ., lit. "I Aim to Be an Adventurer with the Jobclass of "Jobless"") is a light novel series by Souffle with illustrations by Neko Nekobyou.

Plot
Without a goal, a boy named Mars Ruina, who spent everyday lazing away, saves a girl named Laina from the attack of a monster. Defeating the monster in an instant, she witnessed Mars' true power, and inquires which Adventurer’s Guild this must-be famous adventurer is from. However, the truth is Mars' Job Class is simply "Jobless." Laina invites Mars to train to be an adventurer under her tutelage. Although having a job class of "Jobless," this exceedingly strong boy somehow or the other aims to become an adventurer. Before he realizes it, he has already formed a harem on the road of his expedient success story.