On the Jung sisters' very first episode of their reality program 'Jessica & Krystal,' emotions went high and tears were shed, showing how much the two loved each other.

Krystal had a special birthday surprise for her older sister, who shed tears at the beautifully lit cake. �The two also cried during the interview portion when Krystal was asked how she would feel if Jessica were to get married.

Krystal said, "I don't think it'd be good," and started to tear up. �She quickly covered her face with the pillow on her lap, which caused her older sister to start crying and do the same thing with her own cushion. �

Krystal told Jessica playfully, "Don't get married," to which Jessica said, "You, too. Just keep living as an old spinster," causing laughter.

SEE ALSO: f(x) Krystal Jung stuns in 30th birthday photos

Also in the interview portion, Jessica said, "Both of us were always shy," and Krystal added that this was the case since they were young. �Jessica said that people used to stare at Krystal when she was young because she was very pretty then, too, but Krystal would always be so shy. �Because of that, she would hide and cry. �

In relation to their complexes, Jessica said, "My complex is coming off rough. �The average person thinks of idols' bright images, but my sister and I tend to not have strong expressions. �If I'm not so lively, other people could get in a bad mood or misunderstand. �I wish they wouldn't think me as rough. �That's my complex."

Krystal said, "I don't particularly want to explain. �This is us, so what could we do?"

Check out the cute and touching clips below!