Brother of a Fire Witch

Prince Haruko only wants to be left alone to build steam engines and mechanical devices, but his sister, the witch Tanoshi, has a problem. After turning people into frogs and single-handedly defeating an army, everyone fears and avoids her. But, as she approaches marriageable age, Haruko realizes she needs a husband, or face death from the Moon Goddess' curse. Their lives become even more complicated after Haruko is ordered to the capitol to marry a noble's daughter who thinks anything mech...