One of the main antagonists of ryuu_ga_gotoku_6
In ryuu_ga_gotoku_7 he's the second in command of the Korean faction Geomijul in Yokohama and in Chapter 10 joins Ichiban's party.
If completing his drink link he reveals his real name is Yeonsu Kim and he is the body double of the original Han Joon-gi. After much speculation how the original was killed in Ryuu_ga_gotoku_6. For this please use han_joon-gi for both to avoid spoilers.