Yoo Jin-Ho is Jin-Woo's best friend. Jin-Ho is fiercely loyal toward Jin-Woo and seems to have a desire to make his own living, which likely stems from his high-society background. A running gag to his character is his odd habit of dressing up in very flamboyant and expensive armor whenever he goes on raids.
Jin-Ho met Sung Jin-Woo at Hwang Dong-Suk's raid party. Later on, he asked Jin-Woo's help in order to become the guild master of the future Yoojin Guild by completing 19 more raids with him in exchange for a building worth 30 billion won (about $26.8 million USD).
As they went through raid after raid, Jinho eventually became Jin-Woo's best friend, and the two ultimately developed a brotherly relationship.
By the time their deal had been completed, Jin-Woo had already become a S-Rank, and thus, the building that Jinho had promised him was of no use to him anymore. As a result, Jinho ultimately dropped his aspiration of becoming the guild master of the Yoojin Guild and opted to join Jin-Woo's guild as its vice guild-master instead.
Jinho then went on to accompany Jin-Woo in their first few A-Rank dungeon raids and even went with him to Japan for the Shinjuku Raid.
