Chapter 4, or "Chp 4", implies a serialized content format, where each chapter builds on the narrative or showcases different aspects of the characters involved. Without specific details on the chapter's content, one can speculate that it might delve into Miyuu's backstory, showcase her talents, or perhaps introduce new dynamics within the series.
This fictional story is just a representation of what the content might be like. If you're looking for the actual content, I recommend searching for it on legitimate platforms or websites that host idol-related videos and documentaries. Girlx Jpidols GOD 008 Miyuu Chp 4 Mp4