My Little Master is an Otherworld Veteran

Laika Galactica was a grave criminal. The punishment imposed on him was the capital punishment of a thousand years of confinement, his mind abraded and not even granted the relief of death. He was locked in what seemed like a perpetual darkness, his flesh replaced each time it decayed. After spending a thousand years—enough time for an average person to go mad several times over—like that, the body he ended up with was that of… a frail little girl. As he was pushed off into the world with no explanation, he encountered a single girl. Her name – “Momose Kaguya”. Her profession – “High School Girl”. This is a story of a girl who wandered in from another world and a Wizard (shut-in) who had lost everything.