XV Episode 2
They protect the eyes against intense solar rays and other bright lights. Caucasians, as their skin color would suggest, suffer a number of health problems due to exposure to sunlight and therefore tend to wear them rather often.
In addition to blocking sunlight, they're also useful for hiding one's gaze, making it more difficult for the wearer to convey their true thoughts and emotions.
Who was it really that Ogawa thought seemed troubled?
Was it perhaps the one who yet yearned for a stage other than the battlefield?