some intersting teori.
inside body of han bi kwang father / "that person" is Jaha Masin (as maryong sword said)
Cheon MA SIN Gun, has a name looks like Jaha MASIN.
CMSG is come from sinji too?
have Ki Absorber, can use Fire Dragon sword, and other sinji technique (only that person who has the technique).
Han Bi Kwang after absorb energy from Ji Sin Gak, become a difference person, like have devil inside him. maybe its Jaha Singong? remember chapter Jir You, HBK fight with Jaha Singong.
CMSG had order diciple to find Jaha Singong Technique (on that chapter).
Jaha Singong, Jaha Masin, Cheo Ma Sin Gun?
hmmm. interesting and mysterious..