Justice, For Book’s Sake, is a quest you will get access to in Genshin Impact at Adventure Level 26. The quest acts as an introduction to the character Xingqiu, a Sword using Cryo party member that you will be able to try out during the quest.
To begin the quest, go and visit the Wanwen Bookhouse in Liyue harbor and speak with Jifang about getting the travel guide. This is when you will meet Xingqiu, who will agree to the travel with you to find a rare book dealer called Chang the Ninth.
Step 1 – Go to Qingce Village and speak with Chang the Ninth
Finding Chang the Ninth is actually the most awkward part of the quest as he is in a pretty large search area. You are looking for a ladder that leads up a cliff, this will bring you to his house. You can find them directly behind the old lady’s pagoda in the center of the village.
Speak with Chang and he will tell you that he had to sell all his books, and then a thug will visit him demanding a huge discount on some Cor Lapis. Chang will eventually find the book that Xiangqiu is interested in, and the charactewr will leave.
Go and find Xiangqiu by following the wait point and and some Fauti enemies will appear. You will get to use Xiangqiu are a trial character, and they can quickly dispatch the enemies.
Step 2 – Know Thyself, Know Thy Enemy
You will need to visit Liue Harbour and speak with the guard at Gentyr Macoai’s house. Macoi is not at home, so go and visit Xinque Kiosk and listen to his conversation. He is up to no good, in league with the Fauti, so speak with Xingiu about his plans. All these steps involve waypoints, so are easy to follow. As a hint, you can climb the outside of the Kiosk building and it will kickstart the cutscene, automatically placing you inside.
Step 3 – Calm Before the Storm, Bookworm Swordsman
Xingqiu will ask you to deliver a letter to the Feiyun Commerce Guild, and the servant you deliver it to, Xu, will ask you to help them out buy buying up Cor Lapis. You will need to visit three vendors in the town, all with waypoints, and buy there Cor Lapis.
After that, head to the Chasm and speak with the Supervisor there. He will need help tracking down his carts, which went missing. This is easy to do, as they are close to his location, and will have a small glistening light on them. Interact with them all, then return to him.
Finally, return to Chang and purchase his Cor Lapis. He will be delighted to sell it to you. You won’t need any Mora, as this is all taken care of by the guild.
Step 4 – Justice Is Its Own Reward
Visit the Commerce Guild at the waypoint and then help defeat the Fatui that show up. It is an easy fight, so won’t be a problem for you. After that, an Agent will appear, who is a tougher fight, but still shouldn’t prove too troublesome.
When you are done, return to Chang to finish up the quest.