Mamoru Hijikata

He is the protagonist of the story. Although he is completely blind, he was once a master at swordplay. To compensate for Mamoru's lost vision, Igawa has developed a device with an outer appearance of a pair of sunglasses, that projects directly onto Mamoru's retina a rendered first-person view of Mamoru's surroundings in the fashion of a wire-frame model. Having learned many real-combat sword-fighting techniques, and with the newly-gained "sight," he is able to engage in direct combat with his opponents.

(Source: Wikipedia)