Yagiri Pharmaceuticals

Yagiri Pharmaceuticals is a Japanese company based in Ikebukuro. Namie Yagiri used to be its Chief until it was sold to an American company, Nebula. While she was Chief, Namie used the company as a means to hide Celty's head. During that time, Namie also had the company kidnap people in order to perform experiments on them.

Trivia
Tall guy: 浅沼 - Morita
 * According to the "Durarara no Subete', the human trafickers who worked for Yagiri Pharmaceuticals (last names only):

Small guy: 森田 - Kanazawa

Fat guy: 金沢 - Asanuma