Shouta Magatsuchi summons Quetzalcoatl, a dragon deity named "Lucoa," by mistake. Surprisingly, Lucoa is not the perilous demon Shouta had anticipated, but playful and content. Despite Lucoa's apparent goal to aid Shouta with his daily obstacles as his familiar, her courageous and eye-catching actions suggest otherwise. Despite constant misunderstandings, their vivacious routine provides numerous chances for them to unconsciously establish a profound bond.