Kocchi Muite yo Mukai-kun

About a 35-year-old office employee named Mukai-kun, who has been single for 10 years now, and still has a lingering attachment to his last ex-girlfriend, Miwako. At work, Mukai-kun starts to notice Nakatani-san, a temporary employee. Caught between an old flame, he cannot let go, and a new encounter, Mukai-kun starts his "spot the difference" love game.

(Source: Mangaupdates)

~~ Adapted from the manga series "Kocchi Muite yo Mukai-kun" (こっち向いてよ向井くん) by Nemu Yoko (ねむようこ).