The Sofmap Background (or Sofmap Wall) is a blue and white checkered background with the Sofmap logo repeated across it.
It was prevalent in the late 2000's to early 2010's in Japan as a commonly seen backdrop for interviews and photoshoots of idol singers, swimsuit models, gravure idols and even porn actresses.

Due to its big presence and distinct look, the Sofmap background became very evocative of sexy illustrations in online communities ever since.

See Also:

• Sofmap Wall on KnowYourMeme