Description:

When Makoto was summoned to a magical world, he finally found his little sister Misaki, who disappeared two years ago, is now reigning as the Demon Lord of her own kingdom! The bratty Misaki might treat him like a dog, but Makoto knows that the tyrannical Demon Lord is also a lost little girl.

Alternative Titles:

異世界行ったら、すでに妹が魔王として君臨していた話。, 魔王妹妹早已君臨異世界, 異世界妹, I Went to Another World, and My Sister Was Already Reigning as the Demon Lord., Isekai Ittara, Sudeni Imouto Ga Maou Toshite Kunrinshiteita Hanashi, Isekai Ittara, Sude ni Imouto ga Maou to Shite Boukun Shite Ita Hanashi., Als ich in eine andere Welt gegangen bin hat meine kleine Schwester schon als Dämonen Lord geherrscht, When I Went to Another World, My Little Sister Was Already Reigning as the Demon Lord, Isekai Ittara, Sude ni Imouto ga Maou toshite Kunrin shiteita Hanas