The cast of 'Heirs' are not teenagers in real life but they sure know how to have fun like kids on the set!

SEE ALSO: [SPOILERS!] Heirs Ep. 10: Five Light Moments

The BTS photos which were unveiled on the 12th show Lee Min Ho and Choi Jin Hyuk actually getting along when the cameras aren't rolling and monitering themselves with the camcorder. Park Shin Hye also gets giddy as she pretends to be part of the camera crew while Minhyuk, Hyungsik, and Krystal take couple shots like models. 

A representative commented, "On the set of 'Heirs', the top star cast's passion and strengthening teamwork is exploding with a synergy effect beyond our imagination... Please continue to anticipate the teenage romance which that young actors will delicately portray even more."

Catch 'Heirs' every Wednesday and Thursday!