Lark is a young boy who dreams of becoming a famous adventurer. Unfortunately, his only skill, "Color Master", does nothing more than shoot ink from the tip of a brush. Despite his desperate efforts, his skill is too weak, and he is eventually kicked out of his party.

Just when he's about to give up, Lark meets Arian, the leader of the S-Rank party "Valkyrie", who teaches him the true way to use his skill. The skill was actually... the most powerful enhancement magic! The only catch is that to activate it, he has to draw the spell directly onto bare skin with his brush. Every time he touches the undressed Arian, she lets out lewd moans, making the innocent Lark's heart pound!! To make matters worse, he now has to cast enhancement magic on all the beautiful members of "Valkyrie"...?!