Season one of Masamune-kun's Revenge has come to a close, but it may not have been the spectacular ending we had been expecting.
The karaoke scene has been used in so many different series that it has become dull now, and it also wasn't presented very well. It was something that they should have presented earlier in the series as a type of filler episode, as it was just too lackluster for a finale. They would have been better off putting the Snow White scene as the finale and then having Adagaki reject him.
Since the series is a romance comedy hybrid, it is understandable they would want to end on a more humorous note, they just didn't execute it well at all. I enjoyed the scene itself, but not as a final episode. Notice everyone crumpled on the phone, Yoshino calling on the phone for help, all due to Masamune's catastrophic voice. He was so happy afterward, and it was his first time too. Can't help but feel bad for the poor guy.
He doesn't even realize that this voice possibly caused permanent trauma to his classmates and friends. At least he enjoyed himself.
And as a thank you for all that he's one, Adagaki offered one favor/thing to him, and of course, he'd ask for a kiss in order to exact his revenge. You have to admire Aki's face, she's genuinely surprised that he's bold enough to even ask. She almost looks creeped out, but that may just be my personal interpretation.
She said yes because she's planning something, obviously. Considering how Masamune has made his revenge on Adagaki his main priority, he's pretty dense. He doesn't even consider the fact that she hasn't really changed, and she's just do something to make him look stupid when he closes his eyes, which is exactly what he does. And now, at the end of a somewhat lackluster episode, we see her acting the same as usual, and we're all back at square one.
We also see this ending scene, which as almost a bit morbid considering the series. They left things off where they could probably start up a season two. The show is rated fairly well, and has become very popular. In Anime Expo 2016, when it first made it's anime debut (I think) or at least gaining popularity, it really made a splash. It's a shame they ended season one so poorly. The possibility of another season is high, as they also have to address a lot of questions and major plot points that they left loose.