Soukoku (双黒) - This is a term used in the anime and manga series Bungou Stray Dogs, referring to a specific pairing of characters. It translates roughly to "Double Black" or "Twin Black."

This is still school, Dazai and Chuya are 14, so Chuya is calmly walking down the corridor and hears the laughter of several people.
Some girls and guys laughed at Dazai because of his appearance, but he just remained silent, looking at Paul, although this is not at all his style.