A Musical Story

(Achievement Difficulty - 7 out of 10 for experienced gamers of rhythm/memorization games.
10 out of 10 who are new to the experience of rhythm games.)
Not a guide more like helpful tips, there's two things to know before going for the star to each chapter.

First - You can NOT earn stars while playing the game with assist mode on, you CAN ONLY have it on AUTO or OFF during the chapters. It's found in the options menu under assist mode (It's automatically on Auto and it's recommended to have it on auto, but if you want to struggle by all means turn it completely off)

Now In order to perfect a chapter you have to not miss a single note in the chapter if you do by any means don't immediately quit the game, play out the chapter, (some chapters have 4 to 8 sections before the chapter ends) you will need to memorize and be patient learning and getting into the rhythm of the game, only then will you be able to 100% all the chapters so again play out the chapter once or twice to get a feel for what you need to memorize to perfect the chapter, then after the picture in the middle of the screen enlarges to full screen pause then hit retry and it starts over the chapter without needing to chapter select. (very handy)

In order to tell if the chapter is perfected (you need to hit every note on sync and not miss a single one) there will be a star in the right hand corner and that's to let you know if the star is visible it's currently "perfect" and once the image enlarges to full screen you will hear a chime to indicate you perfected the level and earn "Perfectly Finish Said Chapter" achievements, if you don't hit the note on time or miss a single note you then have to start over by pausing the game immediately and hit retry, it can get annoying by watching the same little cutscenes over again at the start but there is skill and effort required to get 100% completion.
(Also if you just normally play through the game there is chapter select and you can go to chapter select to see which chapters needs to be perfected, you will tell if it is if the chapter has a star in the middle of the screen on whatever chapter your about to select)

Second - A1exRD summited a warning for players on the bonus chapter - "After getting a perfect in every chapter, the credits roll, and you need to press 'A' at the end of the credits to start the bonus chapter. From what I can tell, if you're away from your controller when the prompt appears, there's no way to launch it in the future (even by replaying the credits) without entirely deleting your save file. I've messaged the devs to see whether they have a solution."

So it seems as though you need to pay close attention to the end credits and hit the A button when prompted, otherwise you will miss out on gaining access to the bonus chapter and not being able to chapter select it.
It also seems if you do miss out on the bonus chapter you will have to delete your cloud save and redo all chapters perfectly in order to access the Prompt action in the end credits just to unlock the bonus chapter again.

Now with the bonus chapter (Bonus Chapter name is PineWood and only unlocks if you perfected all 24 chapters and hit the A prompt after the end credits) it will be just like the other chapters, except this chapter has 9 segments (patience is required) play through all 9 sections once or twice to understand the patterns and memorize them, then after the chapter is done hit pause then retry then try to hit every note on time and perfect the chapter, if not then just keep retrying till you do, once you do you will unlock the Love Is All and Voodoo Child achievements.

Good luck everyone! ✨🧁✨