>>1926581Kirino has quite high tsun ratio in the beginning, and because of the past events between the siblings, it is almost impossible for Kirino to directly show her dere side to her brother right from the start. Overall however, she goes from high tsuntsun character to a helpful tsundere little sister that she is currently in the novels.
The anime currently only covers the first half of the story, and thus, only the first half of Kirino's character development. If you want to play it safe, you might want to wait until next year when season 2 airs and Kirino should receive quite significant transition towards her dere side.
(Sorry about the wall of text, /c/. Just trying to help.)
