Uh.. we figured out that the black diamond symbol stands for 18+ content. Just so that everyone understands, the symbol means that there are sex scenes in that chapter. There will be more of these chapters in case anyone of you wants to skip it. Usually, there will be more of the story after or before these scenes.
~ReanKun & ann@chan & Rainn-chan
ℝeanとann@ 
Lol, got it~
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