"You must take better care of yourself."

This seems to be spoken in a mostly perfunctory manner, as Shu would not be fulfilling her duties if she did nag him at least a little bit. She does, however, lightly tap his hand with two fingers as he attempts to reach for the lunchbox.

"Go wash your hands."

This is not a nag, but a command.

Whenever he does so, she will have cleared a small space in an area she deems suitably hygienic for his lunch.

"...You should start to eat. But there is something important I think I need to tell you."