The quote has been translated to "Fun is infinite - Sega Enterprises - Signed: Majin" Majin is Japanese for devil, so it says "Fun is infinite with the devil." Sega apologized for this saying they would never do it again, and it was simply a joke to the JP/EUP players.
Pre-Super Genesis Wave. In the Sonic The Hedgehog and Sonic Universe comics, their relationship is similar to the games. The comics started as a promotion for the animated series, so Sonic has a relationship with Sally Acorn from the beginning.