@adumin
Well, best part yet is that after they still continuing it they want some instant change for MC like in some battle manga at least- after if this would happen they will just complain even more how no sense and bad it is. When one of key factor for K, O is that it's slow and keep everything very grounded. Definitely not story for everyone, but at same time no so bad to complain so much about it.
@YamiryuuZero
To be honest like this much more than any Seo Kouji works and it's nice change from other rapid plot change mangas. This one (K, O) is also very slow but author keeps very good eye on timeline (pretty much we have dates at least each arc and story progression is link to that in very good way) and events make sense when in Seo works every next work is total mess and things jump past/ present like in Suzuka and Fuuka. Well, after Seo just started random drama and killing characters randomly with same truck non sense so it's even worse.
@Adiazgonz
Well it was way more subtle. But I'm glad that Umi ended as decent guy who is one sidedly in crush/love as at the end he helped her as friend- and him comparing himself to Chizuru as idiots who aren't honest with theirs feelings was great. Especially, when it was so easy bait for author to force drama.
Also few big developments. Most important Chizuru change of thinking- no longer "Kazuya is good friend. I don't have any romantic feelings for him" to conflicted "I don't know what he is for me" and she will have face her feelings, decided and move on.
In addition, this is second time that Kazuya is using past narration so in the present he is at least dating or married to Chizuru.
As for predictions pretty much now Chizuru will be very self aware around Kazuya what would lead to lot of awkwardness and misunderstandings. After movies will get media noise I'm pretty much sure her father will show up to mess things up.