Song Ji Hyo is an accountant working in a public accounting firm with her best friends, Han Ji Min and Kim Min Jung. She has been dating with Kim Jong Kook, her best friend during her college years in different department (Ji Hyo in accounting and tax, Jong Kook in IT), for 2 years. They met when Ji Hyo had her cell phone repaired in an outlet in a mall near their campus, named “HAPPY CELLULAR”. Jong Kook was the one who fixed her cellphone that time. He was also their university’s representative athlete for Tae Kwon Do matches and works part time in HAPPY CELLULAR, then Ji Hyo always attend his matches and cheer for him.

They live in an apartment but neighboring rooms in Seoul. They love and feel comfortable with each other, Jong Kook with his hobby with motorcycle and simple life as mobile phone technician and Ji Hyo with her busy and a bit static job.

But Ji Hyo never knows  another way Jong Kook earn for living that enables him to always be there for her every night but makes him extremely difficult to have free time to date.