Yosuga no Sora/WMG
In the anime, at least, Haruka and Sora actually drowned.
Scenes showing them alive after Haruka loses consciousness underwater are either dying hallucinations or their afterlives. The text message that Kazuha claimed to receive was actually a fake, sent by herself or possibly by Akira.
The biggest clue that this is the case is the final scene of the anime, intended to seem like a Book End of the first, showing Haruka eating pocky on a train with Sora in the opposite seat. Sora then kisses him passionately. However. Sora's stuffed rabbit is shown to be intact, when it is shown to have been pretty thoroughly destroyed by Sora before she went to commit suicide.
As of December 2019, MyAnimeList user Kembobo addressed the death theory and was able to prove the twins are alive through evidence and logic on the poll 'Are Haru and Sora alive?'
The rabbit was confirmed to be an editors mistake, and, thanks to a scene being curiously cut from the anime, we never find out that Sora is in fact a great swimmer, and saved Haru's life from drowning when he was accidentally pushed into a swimming pool, and due to shorter dialogue after the lake, Haru never asks how they got out (she pulled him out with a renewed will to live after he asked for her to help him while drowning). Despite the overall darker tone the anime takes, the intention wasn't to kill the twins or imply that the twins died, and just came down to a mistake and lack of context I have no idea where you found that information regarding the bunny being an editor's mistake. You are either very good at searching, or you just lied about it (pardon my scepticism ). Either way, it's irrelevant; the hits of them being 'dead' aren't strong enough to be considered proof. The torn bunny could have easily been replaced with a new one and Kazuha's message being a fake doesn't actually prove they died. Also, Akira couldn't have been the one to send it. She was the one who asked Kazuha whether there were other messages, which means she genuinely believed the text to be true and the twins to be alive. Which also proves that, while she was indeed the shrine's caretaker, she didn't find any corpses in the lake, despite being the only person who could've found them, since she lived there. Haruka and Sora surviving couldn't have been a dying hallucination either. After all, Haruka, while chasing after Sora, didn't have a chance to see the stair steps atop which he would have been lying afterwards with Sora, which means he wouldn't have been able to hallucinate being on them in the first place. Sora, on the other hand, didn't notice Haruka's bruise on his left knee, or the barely visible belt he was wearing, since she only turned around for a mere second before turning her back to him and running towards the centre of the lake. Yet, in the scene where they are lying on the stair steps, you can see both the bruise and the belt, which means Sora wasn't hallucinating either. The only possibility left is that what we saw was their afterlife. However, even that is to be excluded, as you can see that they are both drenched and Haruka still has the bruise on his left knee, which means they still have their bodies and they are not lying at the bottom of the lake. The biggest clue that they did survive though, comes from the trail of water which leads from lake's surface all the way to where the twins are lying, which undoubtedly proves that someone (most likely Sora) dragged the both of them up those stairs, to safety. If the lake scene isn't enough to confirm they are alive, here's a bit more of evidence. When their friend are circling around the house, the first (and pretty much only) thing viewers tend to notice is Akira spotting the torn up bunny. What hardly anyone notices, however, was what Nao sees inside the house: the futon atop which the twins would sleep. In an earlier scene, when Haruka discovers Sora's suicide text, which was the last time anyone was seen inside that house, there are 2 cushions, both placed on each corner of the futon, and the blanket is set so that it covers only half futon. What Nao sees, however, is only one cushion, which is more centered, and the blanket covers pretty much the whole futon.Unless Goldilocks lives in the Yosuga no Sora universe, everything being placed differently is a clear hint that the twins went back home and slept there AFTER the lake scene, which in turn means they are indeed alive. Finally, in the train scene where they are seen eating Pocky, Haruka has next to him a suitcase, a reminder that they are leaving the village forever, which is why they wouldn't have bothered to clean up the house (or tidy the futon for that matter), since they would never return there anyway.
While I agree with everything you stated, I hate to break it to you, but the bunny was indeed confirmed to be a mistake by none other than the editor himself: because they were rushing to finish the last episode, and because Sora was almost always drawn with her bunny, the poor guy forgot that she had destroyed it, and ended up drawing her with it on the train. He did say he was surprised however that so many people believed them to be dead because of such a minor mistake. For one, he said he didn't understand how the bunny and the fact that they were dead were connected. He also added that even if people interpreted the bunny as a death flag, for whatever reason, the lake scene, the text message and the suitcase should have made it more than obvious that the twins were alive, even to the most sceptical of viewers. In other words, you're right, they're alive. Personally, because I hate the idea of the bunny being a mistake, I like to think that their friends were searching the house while Haru and Sora were still at the lake, making love and that the bunny we see on the train is the broken one Sora sewed back together. She was shown to be sewing in an earlier episode.