What an emotional rollercoaster of an episode! We’re back to the tense atmosphere right away as we see Mayuri waiting under the rain for Rintarou to finish class. It’s raining and that adds a bit more gloom to the whole mood. It’s obvious that their interactions are somewhat tense under the pretense of talking like they always do. Rintarou talks a bit about his possibilities of studying abroad and Mayuri encourages him, but soon enough she starts feeling uncomfortable by his attitude. Mayuri knows Rintarou is hiding inner pain, but she doesn’t know what she should do to ease that.
Later on she meets Ruka and they talk a little about the upcoming Tanabata. Mayuri confesses that her wish has always been to become like Orihime-sama and Ruka tells her that she will certainly become Rintarou’s Orihime, but Mayuri is adamant in saying that this is not the case. It’s really a sad moment as Ruka is consoling her, but I’d say both of them are shaken up by unrequited feelings for Rintarou. It was a rare chance to see Ruka in a more masculine role, too. That was a bit shocking, but pretty nice.
The big event that happens right after this in the episode is Rintarou accidentally finding out that Daru and Maho are building the Phone Microwave version 2. Rintarou gets really upset over the prospect and Daru is kind of playing it down so it’ll seem like they’re doing something harmless. I think it’s quite a difficult thing to take sides in this argument, but Rintarou really doesn’t understand why anyone would want to build a time machine again. The suffering still feels so fresh to him, all the memories of his failures and the sacrifice he had to do, that he’s very angry and lashes out at both his friends. He asks Maho if she knows what she’s getting into and accuses her of wanting to murder Mayuri.
Coincidentally Mayuri is standing outside! She hears pieces of the conversation where they talk about what would happen in the timeline where she dies, World War III is avoided and Kurisu lives. In the heat of the moment Daru gets really angry too and punches Rintarou in the face. This positively defuses the situation and takes the argument down a notch. It was a really distressing, but powerful scene. Once Rintarou suggests to get some fresh air and sees Mayuri’s umbrella outside, I also sensed a future confrontation coming on.
Maho and Rintarou talked in the roof for a while. There was a great line during this scene where Rintarou says ‘God does not tolerate human arrogance.’ It really is interesting to think of time traveling as a god-defying occurence and then the consequences of it, a punishment. I liked that Maho seemed unsure of Rintarou’s affirmations of what the world was like, but I don’t know if I would say she’s right too. Eventually Daru comes to try and make peace, but Rintarou leaves.
Later he runs into Mayuri at a park they used to frequent as kids. This scene was positively heartbreaking. The fact that Rintarou chose to save Mayuri is something he doesn’t regret. 
He knows that this is what Kurisu would have wanted to, but Mayuri is torn precisely because she would have wanted to do the same, I believe. She complains that he looks as if he’s suffering all the time even though he says everything is all right now. I was also personally upset by the fact that he says he doesn’t want anything to tarnish the moments they have now, but he often avoids spending time at the lab and with Mayuri, even if he doesn’t do it deliberately.
The episode ends after this very sad scene of them at the park and I’m really wondering if there is a possibility of this world being saved and Rintarou not having to choose. Time will tell!