A few days later, Du You no longer envied the sisters' Space Arrows. After a few days of adaptation, Du You realized that there was a significant problem concealed in the sisters' use of the Space Arrows.
It turned out that Space Teleportation put massive pressure on their bodies. At first, it wasn't evident in their experiments, but later Du You and the others recognized it. Using the Space Arrow for teleportation, if continuously used, could only be done a maximum of ten times before the sisters would start to feel numbness and pain in their bodies.
If used more than twenty times, their bodies could potentially collapse under the strain.
It meant that even during battles, the two could not use teleportation for prolonged periods. At most, it could be used as a crucial skill. After investigating, Du You found that most teleportations had this shortcoming.