Gonna sound like everyone else here, but my thoughts:
Remove the constant head bob, it doesn't move in a natural way and is just annoying
Move speed of both characters needs at least a 100% boost, especially the walk speed of the sister
Dialogue....wtf seriously, it's unskippable and painfully slow, there's no reason there should be a ~5 sec delay before going to the next line. It needs to be able to be clicked through at the least.
The story, once again wtf, nothing makes sense. It's vital that sister takes her pills on time according to parents. "Guess I'll make sure to do my homework first, oh the phone is ringing, I need to answer that and talk to the parents for an hour."
Haven't even mentioned how the grammar is really bad and regularly switches between calling the sister "her" and "he"