That is first npc you meet in game. Great master ZiDai is the one who learn you how to begin the game.
His quests are introduction to game, and it's hard to play that game without those basics.
He learn you how to buy sth, how to equip, which NPC is for what etc.
He is helping you to get your looting pet and he is helping you to hit lvl 7 easy.
In his quests you get:
Armor and legguards for your class and lvl,
Fortune Pig (pick up loots for you (lasts 3 days)),
Some Xian reputation,
And basic informations <- that is the most important.
His quests are type of, go-to, bring-from. Easy and really worth to do.