The guy who played Tomoki's name is Hiroki Narimiya, by the way
He was also in the Nana movies and he was in Azumi and Rempo Noir, and probably oter things I can't remember.
I think that confused everyone who saw that movie, but I think sillygodxdisco is probably right. Although I thought it just meant that Tomoki was the reincarnation of Sayaka's brother.