Kuroko certainly loves Mikoto. But I feel like Kuroko's attraction to her onee-sama comes from three things: Mikoto's self-confident attitude is kakkoii, her desire to have status by associating with a level 5, and lots of hormones. Seriously, sometimes I wonder if she's descended from Ryo Saeba.
"Kitto daijoubu da yo." - Sakura Kinomoto