Yes, definitely check Qi Gong out. I do the Wudang Five Animal Qi Gong, which is soft internal martial arts. There are so many different forms and types of Qi Gong, but this one mimics the movement of the dragon, tiger, leopard, snake, and crane.
Here's a good video to watch of a pro with amazing flexibility. These movements should be practiced every day to open blocks and energy channels in the body. He doesn't give instructions on the breathing here, but there are numerous videos that this will lead you to:)