Didn’t See That Coming by Jesse Q. Sutanto

A hilariously fresh and romantic send-up to You’ve Got Mail about a gamer girl with a secret identity and the online bestie she’s never met IRL until she unwittingly transfers to his school, from the bestselling author of Dial A for Aunties, The Obsession, and Well, That Was Unexpected.

Seventeen-year-old Kiki Siregar is a fabulous gamer girl with confidence to boot. She can’t help but be totally herself… except when she’s online.
Her secret? She plays anonymously as a guy to avoid harassment from other male players. Even her online best friend—a cinnamon roll of a teen boy who plays under the username Sourdawg—doesn’t know her true identity. Which is fine, because Kiki doesn’t know his real name either, and it’s not like they’re ever going to cross paths IRL.

Until she transfers to an elite private school for her senior year and discovers that Sourdawg goes there, too.
But who is he? How will he react when he finds out Kiki’s secret? And what happens when Kiki realizes she’s falling for her online BFF?