Moto Dorei desu ga, Oni no Dorei wo Kattemitara Seiryoku ga Tsuyosugiru node Sutetai......

It has been seven years since Sora Ono was sent to another world, where she was enslaved. Because of a clerical error, her "slave" status was revoked, and Sora walked away a free woman. Then one day, she purchases a slave... (Source: MU)