Shiitagerareta Tsuihou Oujo wa, Tenseishita Densetsu no Majo Deshita

The moment her uncle pushed her out of a window but failed to kill her, six-year-old Princess Claudia remembered everything. In her past life, she was a legendary witch who commanded a veritable army of magicians. She possesses a magic that can leave the world at her mercy! Never mind her cold reception in this life! Claudia decides to live free of worldly worries. She makes a servant of a handsome but unfriendly boy, Noah, and sets out to do whatever she pleases by using the advanced magic that once shook the world, sweeping away her opposition in the process! Unfortunately, using so much power makes her so sleepy… Zzz... Claudia rests easy in the arms of her unwilling servant after using too much magic. Here begins the story of a legendary witch ready for a comfortable, leisurely life with her grumpy, raven-haired servant! (Source: J-Novel Club)