Cinderella Boy (Punko)

When a fame-obsessed boy named Chase finds a key that allows him to walk into any storybook and take the place of a character in it, he’s offered a chance to earn a wish for anything he wants. The only catch? He's always the heroine! Meanwhile, other forces are searching for his key...especially Chase’s rival, a handsome but malicious young man in possession of another key, who is determined to kick Chase out of the storybook biz for good.

(Source: Webtoon)