There's Love Hidden in Lies(2015)

Uso ni mo Koi ga Iru

There’s nothing worse than having the guy you’ve secretly crushed on for ten years say you’re like his mom. When Natsume Mishima is given a chance to be in a fake relationship with Chikage, the hottest guy in her class to make her crush Yuuki jealous, she takes it -- even though she hates lying. Will this web of lies get her the guy she wants?

(Source: WEBTOONS)