"Let me start by saying what is the best thing she does for me. Every time she smiles, it just adds that little spark I always need in my eyes," Hrithik said in an interview.
The actor is currently busy promoting 'Krrish 3', his new superhero thriller slated for a November 4 release.
Sunaina enjoys the small little things that her brother does for her.
"He just keeps doing these small things everyday, which means a lot to me because small things later on become big things... it could be a hug, a smile on his face, and it could be seeing him happy," she said.
Sunaina was diagnosed with cervical cancer almost five years back, which she fought and overcame.