▁Several ▁months ▁later , ▁he ▁played ▁another ▁historical ▁character ▁in ▁Kim ▁Su - ro , ▁The ▁Iron ▁King , ▁as ▁the ▁tit ular ▁founder ▁of ▁Ge um g wan ▁G aya . ▁ ▁In ▁ 2 0 1 1 , ▁Ji ▁S ung ▁star red ▁alongside ▁Y um ▁Jung - ah ▁in ▁Royal ▁Family , ▁about ▁the ▁power ▁plays ▁within ▁a ▁cha ebol ▁family . ▁Later ▁that ▁year , ▁he ▁was ▁cast ▁in ▁the ▁work place ▁rom antic ▁comedy ▁Prote ct ▁the ▁B oss . ▁In ▁a ▁departure ▁from ▁his ▁usual ▁serious ▁roles , ▁Ji ▁S ung ▁played ▁a ▁d ork y ▁man - child ▁with ▁a ▁pan ic ▁dis order , ▁who ▁m atures ▁and ▁lear ns ▁to ▁run ▁his ▁father ' s ▁business ▁after ▁meeting ▁a ▁fe ist y ▁secretary ▁( play ed ▁by ▁Ch oi ▁K ang - he e ). ▁ ▁From ▁ 2 0 1 2 ▁to ▁ 2 0 1 3 , ▁Ji ▁S ung ▁played ▁a ▁gift ed ▁se er / ge oman cer ▁in ▁The ▁Great ▁Se er . ▁His ▁fict ional ▁character ▁becomes ▁a ▁" king maker " ▁to ▁Y i ▁Se ong - gy e ▁( play ed ▁by ▁Ji ▁Jin - he e ), ▁the ▁general ▁who ▁leads ▁the ▁over throw ▁of ▁G ory e o ▁and ▁establish es ▁the ▁Jose on ▁D ynast y , ▁becoming ▁its ▁first ▁king ▁T ae jo . ▁ ▁In ▁late ▁ 2 0 1 2 , ▁he ▁star red ▁in ▁adult ▁rom antic ▁comedy ▁My