Wild Cardz, known in Japan as Jaja-uma Quartet (Jaja馬!カルテット), is a Japanese manga series written by Noritaka Suzuki.
This anime has very little fan service compared to the director's previous works and instead of the cute magical girl genre, the focus is more action-oriented with styles similar to a shōnen series.
Some of the characters and enemies are named after game pieces and cards to coincide with the theme.
Sunday is the poker-faced leader of the Crown Knights who has a fearsome power hidden underneath and will only use it to save the Card Kingdom.
She mostly stays behind and orders the other Crown Knights to defend the kingdom and only chooses to go into battle when necessary.