Hatsukoi Harassment: Watashi no Koi ga Konna ni Jigokuna Wake ga Nai

Unable to convey her feelings to her admired senior, Haruta, Natsuki bid him farewell as he graduated. A few years later, the two of them managed to meet again by fate, and just when it seemed like their first love was on the move again, what Natsuki saw was Haruta, who had turned into a power-harassing boss from hell!
(Source: Drama-Otaku)
~~ Two versions: (Broadcast) || (Hulu)