Summertime Rendering is a very interesting manga overall. It's not unique in it's way of using time travel or parallel universe concepts, but the way the characters all feel distinct and you can definitely find at least one to sympathize with is what makes this and entertaining read.
There's going to be a lot of spoilers so I'll just hide them if you would like to read it yourself.
The world of this manga is quite plain, I didn't feel attached to the island or it's culture. It wasn't drawn too detailed either, but it's okay since the characters make the whole story what it is.
Character wise, like I already mentioned, every one of them is very distinct, if you want a young guy that tries to calculate his moves and occasionally thinks objectively because of his past mistakes, check. Maybe you want a strong female protagonist that can kick everyone's butt and still stay the cutest and most lovable, check. Maybe you want that one annoying second female that keeps having unrequited love that the protagonist has to save, but it's okay because she's actually pretty chill, check. Or maybe you want pretty good villains that do reflect actual evil and greed.
I'm a sucker for when the evil guys are actually
Spoiler, click to view
humans overcome by greed for more. It's a great concept because it's true to life. Most humans can turn to the dark side very easily, just by temptation alone. Shinpei:
Spoiler, click to view
I do like him and the way he's able to take a step back and look at the situation objectively, I think we all wished we could do that. I just want someone to clarify this for me. At the end of the manga, Shinpei gets the awakened Hiruko's eye from Ushio, right? And that's been happening for a lot of loops in parallel universes. But does that mean that Shinpei can still loop? Not that it's needed now that everyone is alive, but is it possible that he still has that ability? Or did Hiruko's eye disappear with Hiruko. But then how did Ushio give the awakened eye to Shinpei at the start and end of the manga if it was supposed to disappear. Overall, mentally Shinpei is the strongest, being able to withstand seeing your friends die over and over and over again, on top of that, being able to kill yourself whenever the time comes takes a lot of mental strength, which is why Shinpei is strong, but it also reminds me of the way psychopaths think. If you have the ability to save your friends over and over and over again, normal people would break down at the sight of their friends dying like that. Shinpei seems to brush it off and look at everything objectively, which is what most psychopaths would do. They don't use feelings, they use logic. Ushio:
Spoiler, click to view
Still don't understand how was she able to be the "different and good" shadow. Is it because of Ushio's overall good being? Was she born from within Hiruko's request to end it all. Like we see at the end of the manga, Hiruko asks Ushio to erase her, maybe that was Hiruko's plan from the very beginning if the plan to go home didn't work out. Maybe Ushio's shadow was created like a plan B. Overall, Ushio is a great character, lovable and you always want her to win. Not too overpowered, but also not too weak. Psychologically she's probably the second strongest of the whole squad, right after Shinpei. Hiruko:
Spoiler, click to view
Apart from it being a god that was washed ashore a long time ago, we don't know much about it. It created all these shadows because of what? Loneliness? I think so. Seeing the being left of the great god Hiruko at the end is heartbreaking. Even if it was portrayed as the villain for the biggest chunk of the story, all it wanted was to go home and live happily with it's family. Sadly, even gods fall victims to human traps Shide:
Spoiler, click to view
There's too many names this guy goes by so I'll use the easiest one of them. The fact that this selfish guys decided to take care of a "god" and in turn saw a chance to control it already says a lot about him. Hungry for power he was. Not only that, but also immortal life and to see everything burn around him. A villain that has no reason to get sympathy from others, unlike Hiruko. The whole armor made of corpses already says enough about this guy. And the fact that he dares to be unhappy with the fact that he can't be reborn again is maddening, the guy lived for 324 years or something and still hasn't learned a thing. All in all, this ending part is for the people that hasn't read this manga yet and would like to try it.
It's good, a really easy and quick read in my opinion. You'll breeze through it very easily. The start may seem interesting, then it gets s little slow and repetitive, but don't worry, it gets a lot better and if you like action, the end definitely has enough of it. A very thrilling story with mysteries to uncover. A great read for the summer.