Compare to the first season, it's not that much different except their relationship gets better. The female teacher do sometimes hold back about flirting with her former student. Which sometimes would cause problem between them but despite such thing I think I like them together. They also try to keep a secret from the teacher's school. But, like i say their relationship gets better that the female teacher would hold hands or show her cute side to her former student. Everything could have taken a different route if the female teacher honestly tell everyone that she has a boyfriend but scared due to an agegap. But because she doesn't do that she has a few guys going for her but only one guy actually try to date but because she already has a boyfriend (former student) she could not return his feelings. If you think of a different way, like if the former student didn't express his love for her after so many years she might and would possible gotten out with that guy.

So that's why you see a few reviewers saying that you shouldn't read but honestly, once you're 18. You are free to date anyone regardless of their age but it's understandable because of moral and other things that the world view. It's a cute and lovely manga and plus the ending made it much better. So, read it if you're curious. Don't let others decide what you can't read. I promise you won't be disappointed. Maybe just a little bit of frustration but it has a good ending so it's fine.