The Heirs production company, Hwa & Dam Pictures, recently posted behind the scenes (BTS) photos of its cast members in various positions of sleep. A representative commented that many of the actors film with only 2-3 hours of sleep daily, and use any time in between shots to nap. Despite the late nights and freezing weather, it was revealed that the actors still push on with a fighting spirit, and always try their best.

Among the pictures is one of Park Shin Hye holding up her own adorably candid shot of Hyungsik asleep.

Aren't they cute? Fighting, Heirs!