Sumomomo Momomo: The Strongest Bride on Earth: Kinu Ayatsuji / Ayatsu Knu / Shintarou Inoue

 Kinu Ayatsuji is an assassin after Koushi.  In episode 19 she disguises herself as a live in house keeper named Ayatsu Knu to get close to her target.  Kinu loves playing tennis and is willing to repair a roof to keep up her ruse.

Bonus: 

Shintarou Inoue is a manga only character.  She is the heir to the Inoue clan and was raised as a son by her father. 

Chivalry of a Failed Knight: Ayase Ayatsuji

Ayase is a D ranked Blazer at Hagun Acadamy who wants to win her fathers dojo back.  She makes up for her low ranking by being deceptive.  Under Ikki's tutelage she greatly improves her swordsmanship and is shown to have a very high amount of stamina.  

Amagami SS: Tsukasa Ayatsuji

Tsukasa Ayatsuji starts out seeming to be just a hard working, nice girl.  It is soon reveled, however, that she has a somewhat pronounced darker side she keeps hidden.  She can be quite cynical, jealous, and manipulative; even to the point of blackmailing Junichi.  Over the course of her arc she learns to love both sides of herself the same way Junichi does.