Larc dreams of becoming a great adventurer, but the only skill he possesses is the seemingly useless “Color Use,” which only lets him flick ink from the tip of a brush. No matter how hard he trains, his skill is too weak, and he’s expelled from his party. That is, until he meets Arian, leader of the S-rank party “Valkyries”, who teaches him the true use of his skill. Its real power? The ultimate strengthening magic! However, there’s a catch—the magic requires drawing on bare skin with a brush. Every time Larc’s brush touches a half-naked Arian, her lewd moans send his innocent heart racing! And soon, he must use this power on all the beautiful Valkyrie members…!? A classic “expelled underdog rises to power” story fused with an erotic isekai harem fantasy!