We don’t know much about Mrs. Tachibana and her son Ryouta except for Aiko’s memories, but what we see is more than enough to know that in a very short time, they suffered a lot. After being a very close and happy family, things started to go wrong on Aiko’s birthday. First, Aiko and her dad were involved in a terrible car accident, where he died protecting her. Then, Mrs. Tachibana had to keep her feelings controlled, as her daughter was the subject of a very dangerous and experimental surgery in order to save her life. And while said surgery was taking place, the Burst happened and she was helpless, watching how her daughter was taken away and everyone around her and her son died at the Matter’s hands. From Aiko’s memories, we could only imagine that their last moments were terrifying.

However, Yuuya Kanzaki revealed to Aiko that that wasn’t the truth. While her memories of seeing her mother and brother run away from the helicopter that took her to safety were correct, Aiko was wrong in thinking that they had died. Instead, they were trapped by the Matter, inside a semi-transparent cocoon filled with an unknown liquid. So that’s another tragedy to layer upon them: even if they could be saved, in the end, they would’ve lost two years of their lives. Not an easy thing to wake up to.

And with this tragedy, they open up our list on the tenth place.

Maho Shiraishi looks very out of place among the divers. She looks very fragile, as if she would be better placed as a kindergarten teacher, or a gentle housewife. This is especially obvious when she takes her time to make food for everyone, trying to make their rations more appetizing despite the situation. She also acts like a mother to all of them, worried for their health and keeping their diver suits and their vehicles perfectly maintained. She’s Daisuke Shinoyama’s partner and what little we know of their past makes it clear that she loves him dearly.

And it’s her gentleness what makes her so tragic. Because she shouldn’t be there, watching the man she loves and the people she cares for risk their lives time and time again. And as they get closer and closer to the Burst’s Ground Zero, she has to witness more death, and even worse, is made complicit of a terrible choice. And yet, she manages to maintain her gentleness. Her tears for those lost are what give her the ninth place on our list.

At first, we don’t see much of Yuzuha Izasu. She appears only in her father’s memories as a very talented girl who loves the violin and is friendly with everyone. However, at some point possibly before the Burst, she suffered a terrible accident that left her in a comma. Since then, her father has been doing everything in his hands to try and restore her consciousness. A little girl in a comma is quite tragic, but as the story unfolds, things get worse.

When the Divers arrive at Ground Zero, Yuuya is captured by the Matter and is sent to a place that seems to be the mental link between the Matter and human brains. And that’s where he meets Yuzuha, who has been lost in limbo, unable to find her way back to her body. The idea of a little girl lost without being able to communicate with anyone and only seeing through the matter as people get hurt or killed by the artificial life form is nothing short of horrifying. And that is exactly why Yuzuha has the eighth place on our list.

One of the most experienced Divers in the team and Shiraishi’s partner. They were together even before the burst, as their dialogue implies they were in the military together. Of all the Divers, he’s the only one who knew Kurose before the mission, and because of that, he feels very responsible for the team. Even more when he finds out that Yuuya lied to them and to Aiko, so he swears that if anyone in his team gets hurt, he’ll get to kill Yuuya.

He’s a hardened soldier, who has seen the horrors of combat. He also had a lot of experience in the darkest, more dangerous parts of the Gorge against the Matter. And yet, he never lost his good heart, or his gentleness with everyone around him. This is what makes it more tragic when he is the first death on the team. His loss is felt hard by everyone, and what makes this death hurt more is that it could’ve been prevented if only the team had had more information about their mission.

These are all the reasons why Daisuke Shinoyama climbs to the seventh place on our list.

Few people shoulder as much guilt as Susumu Kurose does. He was one of the original team of researches in the Kiryu Biotech Research Facility, and was also the developer of the Cell Assembler technology that helped the project. Single and apparently carefree, he was also one of the doctors in charge of Aiko Tachibana’s care once the Burst happened. At first, it seems that he’s just one of the many people trying to keep her in the dark of her true nature, but soon we learn that he is one of the very few allies Yuuya Kanzaki has in his mission to undo the Burst.

It’s when you realize that he is the only person who knows who Yuuya Kanzaki really is and what their connection to the Burst is that the true tragedy of his life comes to focus. He’s sacrificing everything he worked hard to get in order to help someone else redeem their sins, and by doing that, he’s also risking his friend’s lives. It comes to a point where you wonder if Kurose made things worse by lying, and then it’s possible to believe that maybe he did, and he knows. Which makes him even more tragic and a worthy contender for the sixth place on our list.

Kaede is one of the youngest of the Divers we met, and Haruka’s partner. At first, it seems as if nothing really worries her. She is in the Diver business for the money and has excellent reflexes, which makes her one of the best. At times, Kaede may seem uncaring and cold, especially with people she doesn’t know well, but Haruka knows that it’s because she has learned to hide her feelings to avoid being hurt. At one point, she implies she’s a runaway, and that she wouldn't go back to her family even if she got paid which hints to a very bad childhood.

Because she’s a secondary character in Aiko’s journey, we don’t get to see much of her or her story. But what we know is enough to make her endearing to everyone. She is completely loyal and easy to anger when her abilities are called into question. Although she doesn’t want to accept it, she’s completely in love with Yoshihiko Sagami and, as she learns to open up, she becomes a bit more obvious in her affections even as she tries to keep her feelings hidden. It’s a paradox that makes the viewer wonder if she will have the opportunity to tell him the truth before the Matter engulfs them all.

Because of her mysterious past, and the small hints of tragedy that we can hear in her words, Kaede has the fifth place on our list.

If you told any of the other divers that Kasuki has tragedy in his past, they would probably laugh. He’s the least experimented Diver we meet and partners with Yoshihiko Sagami who, most of the time, seems to be there to keep Kasuki out of danger rather than to pay attention to the mission. Kasuki is very outgoing, expressive, and friendly, which makes him stand out among the divers that are helping Aiko. At some point in his past, he lost his right arm, but because his family has a lot of money, he got an artificial one, so he doesn’t really seem to suffer from the loss.

What makes Kasuki tragic is his big heart. From the moment he met Aiko, he fell in love with her and tried hard to make her feel welcome among the Divers. He was always there, trying to cheer her up and assure her that they would find her family, even when he could see that Aiko was more interested in Yuuya. And here’s where the tragedy begins, when Yuuya reveals that Aiko is not real, but an artificial brain created to keep the real Aiko’s body working during the surgery to save her life and that, for the Burst to end, she has to die. Kasuki then has to watch the woman he loves insist that she’s not real, that she can’t be loved. That, and the last twist of the series, are what make Kasuki earn the fourth place on our list.

The head of Kiryu Hospital, and thus, the man in charge of Aiko’s treatment and care. He also used to be part of the Kiryu Biotech Research Facility and one of the three doctors who were in charge of the artificial lifeforms. While this would mean that he’s the man to come to with questions, the truth is that Aiko and Yuuya spend most of their time running away from him because he is not willing to destroy the Matter yet, as he is convinced it holds the key to saving his daughter.

This makes everything he does tragic because, later on, we find out that the Matter itself is what’s keeping Yuzuha from reaching him. As she is connected to it –something that may have been done before the Burst but is not really explained- she can’t find the way back to her body. So while the solution would be to just turn everything off, which is what Yuuya wants to do, Kyousuke is convinced that what he needs is more Matter. So he is, effectively, working against his own goal without knowing it.

Because he is his own worst enemy, and how tragically his story ends, Kyousuke climbs to the third place on our list.

Aiko Tachibana seems to have had it pretty rough. As we said in the opening of the article, she was in a terrible car accident that killed her father and put her in a wheelchair, even after a very dangerous life-saving surgery. But that is just the beginning of the tragedy of the girl we get to know as Aiko. Once Yuuya manages to get her away from the school and the watchful eye of the Kiryu Hospital, he explains to her what the surgery was: Her human brain was put in an artificial body, and an artificial brain was put in her body to keep it alive during the operation. This was what caused the Burst, so in order to reverse it, they need to put the original brain in the human body and vice versa, which will effectively kill the copy.

This is hard enough for poor Aiko, as she really doesn’t want someone –even an artificial copy of herself- to die. Still, she wants to save her family, so she soldiers on with Yuuya and the Divers to Ground Zero. And that’s where she finds out the truth: She is not the original brain, but the artificial brain, and thus, she’s the one who has to die for the Burst to be over. And this is where her true tragedy begins, when she has to decide if she’s a real person deserving to live or a copy of the real Aiko who should die to let the real human live.

Due to this impossible choice, and the way it’s resolved, Aiko earns the second place on our list.

Yuuya Kanzaki is a man of mystery. We meet him when he is introduced to Aiko’s class as a new transfer student and no one knows anything about him. Some students suppose he’s a “burster”, an orphan from the Burst, others that he may be rich. But they all are wrong as, in fact, he was only there in order to make contact with Aiko Tachibana and make her trust him enough to get her away from the Kiryu hospital. Once he does that, not only do we realize he is part of a group dedicated to study and stop the Burst, but that Yuuya Kanzaki is not even his real name. Legally, he doesn’t exist and everything he used to get close to Aiko was faked somehow.

It’s not until much, much later that we find the truth. Just as the Aiko Tachibana we know is an artificial brain inside a human body, Yuuya Kanzaki is a human brain inside an artificial body. He was originally Yura Toshihide, the doctor in charge of Aiko’s surgery and thus, the one responsible for the Burst. He got fatally injured in the event, but thanks to Kurose and an artificial body that was not reclaimed, he managed to live and create a new identity for himself. And yet, he can’t stop feeling guilty for every life lost in the Burst and is determined to atone for his sins, even if that means dying again.

Because of the guilt he carries, and the fact that he has to kill an innocent in order to undo his greatest mistake, Yura Toshihide, now known as Yuuya Kanzaki, earns the first place on our list.