Candy Boy (2008)

Yukino and Kanade Sakurai are twin sisters that live together in a high school dorm. Although they are twins, they tend to act romantic toward each other, holding hands and going on dates. One day, Kanade sees Yukino hanging out with a new girl, Sakuya Kamiyama. Realizing how much time these two spend together, Kanade assumes they are dating, and she begins to distance herself from her sister. Yukino promptly notices and pleads with Kanade not to leave. In reality, Sakuya has only been asking for advice about Kanade, revealing her obsessive love. How will this love triangle play out?