Assassin × Cinderella is a Manga/Manhwa/Manhua in (English/Raw) language, SUGGESTIVE
series, english chapters have been translated and you can read them here. You are reading chapters on ManhwaZ fastest updating comic site. The Summary is
Neneko is spying on a rival organization's assassin, but her true identity is revealed, and the condition for her safety is "marriage"!? The world's sweetest and most dangerous «Contract Marriage» begins!!