Eiyu-Oh, Bu Wo Kiwameru Tame Tensei Su, Soshite, Sekai Saikyou No Minarai Kisi

Story:

King Inglis, who devoted his life to his country and people, has a dream – to live freely and improve his skills as a warrior. This wish was heard by the goddess. Having reincarnated the king, she sends him to the distant future, but as a sweet girl! Moreover, at the age of 6, it has been declared that she is unable to be a knight, despite what comes from a knightly family.