The new DRTA part which includes the middle part of the third trial will release tomorrow on YouTube! My subs will be included, so you can watch even the premiere with English subs
This post will contain spoilers up to the end of the first part of the chapter 3 DRTA trial
I would like to explain a popular theory in the Japanese DRTA fandom, the theory is about Coco Hashizawa and Kokona Arumada being the same person.
The main reason for this, is the strange factors revolving Hashizawa's death.
First of all, the Body Discovery Announcement does not play for her death. The guys chalk it up as it being drowned by the loud music, but it's worth noting that even the other group only hears the BDA for Marin's murder.
Next, we have the Monokuma File. Its wording is very vague, and uses the term "All victims", rather than naming the victims, or even just saying "both victims". "All" could stand to mean just a single person, and it's even highlighted.
This brings us to two possible conclusions: either Hashizawa is still alive, or her body is a fake.
Let's examine both options:
1. Hashizawa is still alive
To explain this, I need to introduce another theory. Simply put: Hashizawa's body was put into the display case, then the display case with Hashizawa inside was put inside of the cooler, and then the contents were frozen. This would explain the missing display case, and Seki witnessing Hashizawa in the morning (with him waking up around 9AM, and Hashizawa's body being found around 2PM), in spite of Hold Nova's testimony about a large body taking at least 6 hours to freeze.
This would also mean Hashizawa had a small space to breath for a few hours, which could have preserved her life for a little time.
There is only one problem with this: according to the school rules, students who don't take part in the class trial get punished. Which would mean that if this applies Hashizawa was silently executed, was spared since she physically couldn't go, or did make it to the class trial grounds. It is also possible that her punishment is being postponed since Hold Nova and the mastermind are currently busy with the trial.
2. Hashizawa's body is fake
A second possibility would be Hashizawa's body being a fake, with the real one having been killed somewhere else. In fact, we never get to see her after Chisa asks her for help with serving, and Hashizawa doesn't do as asked despite agreeing to it. So, there was the option that she was killed early and a dummy was used to mimic her body. Unfortunately this theory doesn't work well, since she was witnessed by both Arumada and Seki after that point in time.
However, if we use both these theories there's another possibility: what if Hashizawa's body was a sort of disguise or doll that was frozen with the display case trick? And Arumada and Seki witnessed someone else with that disguise on?
With this in mind, let's talk about Kokona and her behaviour, especially in relation to Hashizawa.
First of all, she's the one who set up the speakers, something that might have given everyone the illusion that they simply didn't hear the BDA, even though it played.
She also tried to stop all attempts to defrost Hashizawa
She's also the only one who could have used the dumbwaiter that connects the green room to the home-ec room...
She also displays a lot of suspicious behaviour unrelated to the incident, such as what Seki explains during the investigation, her lack of surprise towards how two-faced he is, the fact she had an e-Handbook and was such counted as a student but was able to avoid all trials, and of course, knowing things she couldn't possibly have known if she only just joined everyone else.
However...if she was Hashizawa all along, her knowledge would make sense.
She could have just been imitating a designer she liked
Or perhaps Coco Hashizawa was Kokona Arumada all along, since she's repeatedly been presented as very talented in various fields, and she might have needed to hide her identity to be succesful, as she is the daughter of a skilled conductor who is also a big misogynist. Then, she'd just be reusing an old design she came up with in the past, before coming up with a second identity. Or if she was only impersonating Hashizawa during the killing game, this might have been her only true design work, which she then re-used.
If Kokona and Hashizawa were the same person it would also solve the problem of mandatory participation during the class trial, after all she is participating! With the fake body being her disguise.
There are also other little reasons which might sound silly but add up with the above context, such as "Coco" and "Kokona" being similar names, and the two of them never have been in the same place at the same time.
On a meta level, it would also solve the matters of "Kokona dying in the chapter she was introduced in" and "Hashizawa not getting enough screentime"