One fateful night, the mischievous thief Esta sets out to rob yet another unsuspecting nobleman of his riches. However, the mansion she targets turns out to be completely abandoned except for the, in her words, whiny and incompetent Yoru. Nevertheless, to her annoyance, she ends up having to take this young man along on her adventures. But despite his appearance, he might be more involved in the town's upsets than she realizes...

[From Official site]