Display device, document reading device, and image forming apparatus

A display device comprising:

• a non-translucent housing;
• a light source provided inside the housing;
• and
• a translucent light display that is transmissive to light from the light source,
• the housing having a through opening that penetrates inner and outer surfaces thereof, and adjacent first and second side surfaces respectively extending in directions intersecting each other,
• the through opening spanning the first side surface and the second side surface,
• the light display having a light guide fitted into the through opening and protruding outward from the outer surface of the housing, the light guide having a smaller thickness in a portion corresponding to a connection. region. between the adjacent first and. second. side surfaces than in other portions thereof.