Masi Oka was tremendous in this scene, as Hiro says goodbye to his mother. He also is now the possessor of the catalyst, at least for a few more minutes.
Both: I know what I have to do! Hiro: (Japanese) I think my mommy can heal my brain! Restore my memory! So I can be a hero! Claire: (English) I think I can stop the catalyst before they put it in me! I could be a hero! Both: I don't understand what you're saying.