異世界行ったら、すでに妹が魔王として君臨していた話。 (Series) favorite_border

[DeepL Translation - needs review] Volume 1 Introduction: When I went to another world, I found that my sister, who disappeared two years ago, had reigned as the Demon King! What lies ahead on the high road of the most cute, the most selfish, and a little lonely sister...! ＜Note: *Additional information added on January 27, 2021. This book is included in the first volume of the paperback book "When I went to another world, my sister already reigned as the Demon King" published by KADOKAWA. T...