Although 29-year-old Son Ho Jun is an accomplished actor with several films under his belt, for fans for the K-pop group TVXQ he will always be known as U-Know Yunho's best bud.

The 27-year-old TVXQ singer seems to believe his friend Son, who can currently be seen in the South Korean television drama "Reply 1994," has what it takes to be a star in his own right.

Earlier this week, Son told the publication Newsen this week that Yunho, who he has known for over a decade, has promised to cameo in Son's next film or television project as long as the pop star's pal has the lead.

"U-know Yunho promised to appear in a movie or a drama if I get the main role," Son said.

And according to the actor, when the TVXQ singer says he's going to do something, he does it.

"U-know Yunho always keeps his promises," Son said. "He has never broken a promise in the 12 years I've known him. So I am sure that he will keep this one too."

He was quick to point out that Yunho has always been a great friend, regardless of his star power, or lack thereof.

"U-know Yunho visited just to eat with me amid his busy schedules, when I was hungry and poor," Son said.

"He is definitely one of my best friends. He supported and cheered for me for over 10 years."

He explained that Yunho's ultimatum was born out of frustration the pair felt that scheduling conflicts prevented the TVXQ singer from appearing on "'Reply 1994."

"I actually asked him to appear as a cameo a couple times," Son said. "He told me he really wanted to appear on the show, but he had a packed schedule. It was a letdown for both of us."

The actor met Yunho while growing up in the South Korean city of Gwangju, the same hometown as that of his "Reply 1994" character Haitai.

He reflected on his other similarities between himself and his fictitious television persona.

"I am similar to Haitai in that we both like [to hang out with] friends," Son said.

"Most of my friends are from the countryside, and we often meet up to talk in coffee shops."