Koujo Tensei: Densetsu no Daimadoushi (♂), Himekishi to Narite Densetsu no Reijou Kishidan wo Tsukuri Musou suru

Synopsis

"I also wanted to be... the strongest in the world." An Arch Mage who died without fulfilling his dream wakes up to finds himself being reincarnated as a member of the imperial family. And what's more is that his new body has a talent for close-quarters combat! This time he holds hope that he finally might be able to fulfill his desire of being world's strongest... But after reincarnating his new name is Evangeline. Indeed, he had become a girl. In her princess life where muscle training and fighting are forbidden, Eva brings dumbbells to her room and wields a sword! And before long, she becomes the strongest!? A fantasy about a tomboy princess' rise to the top! (Source: Kodansha, translated)