Gunnar Lundström is a member of the Illuminati and part of the Guard Division. He and his twin, Gunnan Lundström are inseparable as they are always seen together.

Both Gunnar and Gunnan have blond hair and are always seen in their Illuminati uniforms. When seen without their jackets, they wear dark coloured tank tops and seem to be very well built.

(Source: Ao no Exorcist Wiki)