UFO Princess Valkyrie 2: Juunigatsu no Yasoukyoku

円盤皇女ワるきゅーレ 十二月の夜想曲

Valkyrie, Kazuto, Akina, Hydra and friends are back for more when the Key of time suddenly appears along with many other mysterious happenings. All seemed to be linked to a person named `Valkyrie Ghost` who`s only goal is stealing Kazuto for herself. As they team up against this seeming unbeatable foe they dig deeper into the mysterious past of Valkyrie`s home planet, Valhalla.

(Source: Anime News Network)