Responses
I think the 5.5 to 7 jump is because some places would have labelled 5.5 as 6, making the other one 7 while others might've had it as 5.5 and then the next one as 6. As for ch 1-5 to vol 4 ch 5.5, everything here is technically from the fourth volume so I guess it would have been more clear if it had vol 4 ch 1, vol 4 ch 2, etc. instead of only having it for 5.5. The three previous volumes to this one are
1. K-sensei no Yajuu na Aijou
2. K-sensei no Yaban na Renai
3. K-Sensei no Furachi na Junai
I see, thanks for the clarification.
It went from ch 1-5 to vol 4 ch 5.5, 7 and then vol 5 ch 1... O_O