TVXQ's Yunho and BoA are known to be fast friends, having come a long way together as label mates under SM, one of the biggest talent agencies in Korea.

SEE ALSO: ADOR CEO Min Hee Jin to hold an urgent press conference later today

Yunho may be missing his good friend dearly, as he sent a handwritten letter to BoA, making sure to keep in touch even from the military. 

BoA uploaded on her Instagram a picture of the letter she received from Yunho with the affectionate words, "It's been a while since I wrote or received a handwritten letter. Friend~ thanks for the reply! Be sure to stay healthy! My soldier friend. My friend Yoon Dol."

Aww. Don't you wish you had a caring person like Yunho as a friend, who is always thinking of his loved one? 

???? ???? ????? ? ?????.. ???~~ ?? ???!! ? ??? ? ??!!!! #???? #??????

A photo posted by BoA Kwon (@boakwon) on Aug 27, 2015 at 7:46pm PDT