Kate Takayama is a supporting character in the light novel and anime series Haganai. She is a nun and teacher at St. Chronica's Academy and the older sister of Maria Takayama. Unlike her sister, Kate is a genuine prodigy, being an accomplished nun and teacher at the age of 15. Like Maria, Kate refers to Kodaka Hasegawa as her big brother.
She is voiced by Emiri Kato in the Japanese version of the anime and Brina Palencia in the English version.
Kate has impressive looks, which can be described as a, "matured Maria". Both she and Maria look Caucasian ("Northern Europe" by words of Kodaka). As such, she shares multiple traits with her younger sister: lavender-silver hair, blue eyes and pale skin. She has a well-endowed body. In Kodaka's opinion, she has a sublime, "ideal teenage girl face" and "perfect proportions". It should also be noted that because of these "maturity" traits, she appears older than she actually is. Another distinctive part about Kate's appearance is the beauty mark under her left eye.
Kate has some of the same traits as her younger sister, Maria. She has also been described as "vulgar". She doesn't seem to mind farting, scratching her butt, burping, and telling dirty jokes in public. Outside of these habits, she is quite composed and serious, Kodaka even got confused of her actual age (in sum with her looks and she gave off impressions of someone older). She has an eccentric viewpoint on life, especially on religion (which in her position is practically the same), thinking that Christianity is a "rebellious" religion. However when it comes to food, Kate completely turns into her little sister, her eyes glow and she falls into a simplistic manner of speech, which is quite similar to Maria's.
It is shown that Kate actually cares a lot about her younger sister Maria, constantly worrying about her and seeing whether or not she is well or happy. She is very grateful to both Kodaka and Yozora for signing Maria up (forcing) for the position of supervisor for their club. She has noticed a large change in Maria that she or the other sisters couldn't accomplish as the members of the Neighbor's club had.
It is shown that Kate might harbor a small crush for Kodaka, but it is unclear if she completely let those feelings go because she knew of the status of both Kodaka and Sena's arranged engagement.