Sennen Oukoku San Juushi Vanny Knights

Japanese Title: ヴァニーナイツ 千年王国III銃士

English Title: The three Musketeers Of Millenium Kingdom, Vanny Knights

Plot
Fujita Kazuyuki is an otaku who turns out to be the one carrying the Millennium Saber within him. That means that he's actually Arest Horn, a legendary hero. Amore Gore, an evil organization of demons, want the Millennium Saber so that they can use it to rule the world. Suddenly 3 girls, Arisu, Airi, and Akira, appear in Kazuyuki's life. When they transform they become the 3 Musketeers of Arest Horn, and it's there duty to protect Kazuyuki until Arest Horn awakens. So these 3 girls move in with Kazuyuki and his little sister and the hilarity begins.