That's Mariya, not Shizu. You can tell the difference because Mariya's mole is under his left eye.

As for why Kanako is dreaming of Mariya when a nearly identical substitute is available, the only reason I can come up with is "She's a moron."

With a sexy guy like Mariya, I needn't be surprised anymore if Kanako (and the rest of the viewers) is already questioning her (lesbian) sexuality.

Kanako is just like the rest of us: Mariyasexual.

"Doctor, Doctor, give me the news..."

"Helloooooooooo, Nurse!"