What makes Gojo wear a mask, then? Gojo needs to hide his eyes since he would get too tired if he used them. He possesses a trait known as Six Eyes that has been inherited from his ancestors. This form of ocular jujutsu is uncommon.
Gojo Sataru has the power of six eyes which makes his vision infinite in terms of seeing cursed energy, he can sense it from a distance. Using this often drains his energy hence the mask.
Even though he has counter measure to this, the Reversal technique, that negates all the information that goes to his brains decreasing the overall dosage of cursed information he is getting from all sources, and conserve his energy.
