how does gyomei see

Gyomei Himejima has heightened senses and intuition rolled into one, so even if he cannot see, he wins out. In a tragic incident he lost the ability to see, however in "Demon Slayer" Giyuu is still one of the strongest figures. Gyomei has the ability to "see" his surroundings and confront demons through an enhanced sense of touch, hearing, as well as an extraordinary capacity for detecting spirit forces. His abilities are so advanced that his lack of sight seems not to hinder him in the least. This may be seen in his fast and precise rendering of the enemy during battle.

As a 'Demon Slayer' manga fan, well, I reckon that Gyomei's vision totally transcends that of common men. He has lost his sight, but the power of his intuition and his perception, even far beyond sight in many cases, are heightened. He uses his sharp senses and a thing called Total Concentration Breathing to react on any movement; taking heed of even the smallest alteration in the landscape around him. His deep understanding can sense the merest aura of an opponent, making him a potent demon slayer indeed.

Despite Gyomei Himejima's blindness, he fights demons efficiently in 'Demon Slayer'. He uses heightened senses and intuition to perceive his surroundings and sense demonic presences.

In the world of 'Demon Killer', His Sense of Touch and Sound, and ability to sense auras, are extremely perceptive. Once blind, he is however a battlefield commander against monsters unequaled. Along with this incredible awareness and understanding of others 'feelings about him, even in the fastest-acting Corps that there are today (the Military Elite/Terrorists Company - in the same sense people are members of M) Gyomei is indeed one of the strongest. Period!