However, their long spell of domination mattered little as Mainz broke the deadlock in the 36th minute through Okazaki, who calmly slotted home moments after Ja-Cheol Koo had been denied by Thomas Kraft.
An entertaining second half started in similar fashion to the first, with Schieber looking dangerous again as he fired wide of the target.
Once again Berlin were punished for not making a breakthrough while on top as Mainz extended their lead in the 70th minute, when Junior Diaz rounded Kraft before setting up Sami Allagui for an easy finish.
Niko Bungert gifted Berlin a way back into the match late on as he handed the hosts a penalty with a clear deliberate handball.
Ronny stepped up from 12 yards, and his emphatic effort gave Berlin hope with just four minutes of normal time remaining.
However, any hopes of a late comeback were quickly dashed by Okazaki, who helped himself to a second with a calm finish in the first minute of stoppage time, following a fast counter-attack led by Yunus Malli.