I think its because he doesn't want to leave the area around the academy.
Gu Yi came to the cafeteria. Even though he is the only prospective student in Shrek Academy, the cafeteria is still open. But the food is not very good. After all, even if Flender is a Spirit Saint, he has no background, and is not a noble, it is normal for him to be short of money.
This is a translation.
"A descendant of traditional Chinese medicine (TCM) practitioners, Gu Yi, finds himself transported into the world of Douluo Continent, where he awakens to the martial spirit most familiar to him from his past life. Will he be able to leverage his own advantages and dominate the continent? Which is stronger, martial arts or spirit skills? Will he assist characters such as the arrogant Phoenix Ma Hongjun, the carefree White Tiger Dai Mubai, the Asura God Tang San, the threatening Ning Rongrong, and the willful Xiao Wu in becoming exemplary figures of the new era? It remains to be seen."
Both of them are siblings and they belong to the same clan.
Douluo: The Way Of Martial Arts
Book&Literature · Darkes1