Ojou, Renai no Ojikan desu.

Ritsu, the daughter of a crime boss, is misunderstood by her coworkers at the company where she works to conceal her true identity. Although she comes off as aloof, she's actually just incredibly bad at communicating with others. The only person she can be herself around is Yaezo, the man tasked to watch over her, who enjoys teasing her to no end.

One day, her father tells her she has six months to find someone she wants to marry! Somehow, she ends up practicing her dating skills with Yaezo! When he whispers sultrily in her ear and melts her body with his silky touch, Ritsu realizes he's definitely not acting like an employee anymore...

(Source: Renta!)