From this part onwards would be the hidden chapters that (obviously) were not included in the major chapters.
These would contain the answers to your questions, e.g. What happened to the days when Winter was sent to detentions? What was Winter and Ten's relationship like before? Where did Winwin go, why didn't he show up in Winter and Ellie's graduation? Where did Irene go? What did Taeyong do during the times Winter needed him the most? And other questions similar to that.
This would be done in random (except for the last three to four parts). There will be a Perfect Ten Special, which includes a sneak peak into TenWin's lives after 10 years, and the years after that.