When Lu Li first went back to the Lu Family, Lu Zhengtan, Lu Suan, and Lu Ni were away.
Back then, Lu Li was wondering how they could leave when the Mystic Armor City was sealed off. Now he knew that Lu Zhengtan brought Lu Suan and Lu Ni to the Demon-slaying Grounds.
There were three entrances to the Demon-slaying Grounds located at the north, the south, and the center. One of them was close to the City of Delicacy. Families lower than the fifth rank were not allowed to know about this and disciples who didn't come from major families could not get into the Demon-slaying Grounds. This was the privilege of being in a major family.
Jiang Qiling promised Lu Li that she will try to bring him to the Demon-slaying Grounds, which soothed Lu Li's nerves. He had matters to deal with at the Deserted World and he must improve on his realm as well. After a year and a half, he should be able to stabilize the Deserted World and the Northern Desert.