Since it's been over a year since I read vol. 5 I reread the entire series before reading the the latest volume. In retrospect, that really wasn't necessary - I had forgotten how - well, non-existent the plot was.
Don't get me wrong, this story is entertaining, but if you even attempt to think about the timeline or what's going on, your head will probably start to hurt, so just enjoy this hilarious smut mixed with really over the top love confessions and plenty of blushing as it is. I can't explain why I like this series as much as I do, but there you go.
(Also, for the record: I am really surprised the publisher is recommending this as "for ages 16+". Because it's really smutty.)