High School DxD: The Chronicles of the Devil Planet

Rias Gremory was a heir to the House of Gremory and she would do anything for her boyfriend Issei Hyoudou, until one day when on a blood moon when she went to sleep in her lingerie, she had a dream from a gentle and kind goddess that she would become a living planet the size of Jupiter in her lingerie with the bust, waist, and, hip size of Akeno Himejima, her own sun and moon, and the power to walk among the stars. When she wakes up, she started getting bigger and bigger until she was the size of Jupiter itself. Now the humans will feel what it's like when a proud centaur becomes a gigantic living planet while Rias and her inhabitants travel the universe in quest to unify the universe.