Choppiri Toshiue demo Kanojo ni Shite Kuremasu ka?

First-year high school student Kaoru Momota just saved a beautiful high school girl, Hime Orihara, from a train molester. One thing leads to another, and they end up going on a date! They have a lot in common: they both love video games, they both jam to their favorite songs on mixtapes, they were even both born in the Year of the Snake. Except... Orihara's first game console used cartridges... and her old mixtapes are all on MiniDisc... and, oh, her birthday is actually 12 years before Momota's! When her secret comes out, she thinks it must all be over... but will Momota really let something like a little age gap get in the way of his love for Orihara?

(Source: J-Novel Club)