Gray tabby cat with red collar near Capitol Square

I lost my gray tabby cat, Mochi, yesterday around 6:30pm after I left the back door ajar to grab the mail. He's a medium-sized cat, about 10 pounds, with a gray tabby coat, white paws, and a tiny white patch on his chest. He wears a red collar with a small silver bell and a paw-print name tag that reads 'Mochi'. Last seen near Capitol Square, around State Street and Library Mall, slipping into the alley behind the Union South building; he's skittish but friendly once he warms up. I adopted him last year and he's my constant companion, so I'm really worried; if anyone sees him, email me at [email protected] and I’ll come right away.