Powerful Opponents

The beginning of the first episode really reminded me of King2hearts ... Both have a powerful and strong willed lead woman and they both have to deal with trouble maker, snobby man with high status in this drama he is the son of the president and end up falling in love

Very similar stories, its like City Hunter light.

Cha Young Jin is the first female to ever work as a bodyguard in the Presidential resident, Chungwadae. Young Jin and Yoo Gwang Pil work as bodyguards assigned to watch over the president's son, Kang Soo Ho. They are assigned to guard Soo Ho for 15 months.

Both have strong female leads that are career oriented and romantic subplots that are really realistic without the frilly fluff. (I love frilly fluff, but somethings you want something that feels real. Both of these do that.) although Powerful opponents is making the open ended whereas when it’s at night is tied up fairly well.