Seisei suru hodo, Aishiteru

Kurihara Mia works in the advertising department of a cosmetic company. When her boyfriend proposes after a long relationship, she rejects him, expressing that she wants to continue her job. The argument finally leads Mia to bring up an one-sided breakup. However, her ex-boyfriend isn't giving up. Stalked by her ex-boyfriend, Mia gets saved by a prettyboy, Kairi, whom she has just met! But his actual identity is...?!

(Source: Serenus-Dreamers)