The entirety of Kouta not being able to forgive Lucy for killing people (namely, his father and poor Kanae), despite that she had been living nothing but a never ending hellish nightmare ever since she was born, and was dealing with an uncontrolable, psychotic side within her, but she still just wanted to be loved by someone (Kouta). Made worse by the fact that, as far as Kouta was concerned, he gained a new friend, one he loved deeply, and the last time he saw her, she casually ripped his little sister in half. Him cradling her upper torso was a real tear-jerker. Kouta calling her out on her psychotic inner voice may have been insensitive, but this was the first time he'd heard of this.
Hell, no-one except Lucy and the viewers know about her past in full. Arguably, this makes the whole situation even more tragic. Had she not killed Kanae and Kouta's dad, not only Kouta would've still had his daddy and Kanae (who knows how different things would've been), Lucy would've been through less heartbreak... and specially one that she brought upon herself, unless the other things that happened.
Five words (manga only): "And then, I killed Nyuu."
The final episode where Kurama and Mariko hear the timer go off and close their eyes, and we see a grainy film of still shots from the life they could have had, with Kurama and Hiromi raising her. It was the last one, with her going happily off to school and them waving to her...
Mariko starting to giggle as she begins to torture Nana. She was born a perfectly normal little girl with a mother who loved her. She could have grown up in a nice house by the ocean and gone to school. She could have had friends and a favourite novel. But instead she was locked up away from any hope; they made her into this irreversibly broken creature with no joy in life other than beating the brains out of someone else.
In the manga, she isn't quite so irreversible... which only makes her death all the sadder. There WAS still the chance of her regaining her sanity and living a better life, but it never happened. Nana cries for this exact reason when she thinks about it after Mariko's death.
Nana's final line at the end of the series: "There are so many wonderful things in this world. So many... good things..." The line was just so powerful after Nana is get beaten half to death, watches the man who has given her reason to live commit suicide with his real daughter, and finally finds the capability to connect with fellow diclonius Lucy just moments before she faces the music.
How about in the anime when Nana was being sent to battle by Kurama... and she asks for the pretty ribbon around his neck? (his tie)
When Nyuu cuts her hair and started apologizing to Kouta for killing his father and sister except he thinks she's apologizing about the shell she broke in the first episode.
"I wish somebody would hold me close now"
Also at the very end of the manga when Kouta finds Lucy/Kaede's letter
See you again!!!
I will always, always treasure this stone.
Ah, I want to wear a wedding ring...
Especially touching when we see Kouta breaking down in tears after reading the aformentioned letter. Despite all the horrible things she had done, he will never stop loving her.
Just to think about how things could have been, and how desperate young Kaede must have been for any kind of love at all to be so grateful for even the little bit of warmth and comfort she received from Kouta.
Just a few pages before that, we see Kouta along with the rest of the characters at the spring festival. He then leaves stating that he has to meet up with a friend. Cut to Kouta standing in front of the stone where he and Lucy used to meet and where he promised to meet her after the spring festival before he had to leave. The next panels then show him coming alone regardless of weather to the same place year after year showing that he hadn't forgotten his promise and continuing to keep it despite Lucy already being dead.
And then... Kouta's daughter sees her two twin friends arrive and they tell her that they've been waiting for a friend for a long time, which basically implies that it's Lucy reincarnated. The now older Kouta turns around and starts crying because he found Lucy again. They were also wearing ribbons in their hair, so they could be two new Diclonious from the virus who escaped persecution — it couldn't be a coincidence that they happened to come to the same spot where Kouta and Lucy used to meet.
Pretty much everything that involves Kurama, Nana and Mariko and Mariko's clones in the same scene. Especially near the end when Kurama mentally breaks down after the death of the original Mariko, who committed a Heroic SacrificeRedemption Equals Death to save him. And Nana sees him like this.
That Mariko tells Nana to take care of Kurama for her before going off on her Heroic Sacrifice. After that happens, Nana breaks down crying over Mariko and all the wonderful things she'll never be able to experience now, and later puts flowers at her grave. That it took till the moment of Mariko's DEATH for Mariko and Nana to finally feel for one another as sisters....*Sniff!*
More from Lucy's past, when her Start of Darkness begins and she begins seeing hellish hallucinations. It can touch a very sore and emotional spot.
"Hey horned-girl! You're not a human, you're nothing but an ox."
"Stupid girl. It's because you trust humans, even though you aren't one yourself. You're different from us because you're not a human... even betraying you doesn't hurt inside that much."
"Could I ever feel anything close to love for a weird girl with horns?" "Then why... have you been so nice to me?" "Because I adore strange animals."
Kouta's last words to his sister before she is killed by Kaede on the train. "Don't say that about my friend! I will hate you forever!", she turns around and begs him not to hate her but before he has a chance to reply the person that Kouta was DEFENDING uses her vectors to rip her head off. She had seen Kaede slaughtering people at the festival and was trying to warn her brother, but he just called her a liar and said he hated her a few seconds before her murderer proved her right. No wonder he was so messed up afterwards.
Then there's thinking about the scene from Kanae's point of view. Once she sees Kaede on the train rather than run away and hide her reaction is to push Keade away and place herself between her brother and Kaede as a shield telling him to get away. To reiterate: a 6 to 8 year old girl went off against a psychic mass murderer whom she knew could kill at a distance, so she could save her brother. That took guts, and it's tragic to hear her yelling at Kaede not to kill her brother only for her efforts to be rewarded with a slap to the face by the brother she was trying to protect.
In the OVA when Aiko Takada, one of Lucy's only friends, dies taking a bullet for her. Lucy's reaction and her pleas to Aiko to hold on really drive it home; you can see her world falling apart as her only other best friend dies right there in her arms. The manga chapters that cover this are even worse, showing just how close the two girls had been to reuniting Aiko with her mother before she died.
The scene where after Lucy reveals her powers to Aiko, her response is not to reject her but to take it in stride and later asks her to go on a painter's retreat with her which they sadly never got to take. It is terribly tragic since Lucy finds a new friend willing to accept her for who she is and had seemed to learn from her past relationship with Kouta: she refuses to kill Aiko's father to avoid making her cry, is willing to take the blame when her friend accidentally kills her father, encourages Aiko to seek out her mother and allows herself to be captured without a protest in exchange for Aiko receiving medical care. She dies anyway leaving Lucy to spend several years of ''living hell'' for nothing
Except, she didn't die at all and Kurama told an outright lie, as proven by the poster on the wall in the last chapter. Heck, she even became an artist. Perhaps her traumatic past, especially her meeting Kaede, had some impact on her work.
What makes it worse is that near the end of the manga when Kouta takes the bullet for Lucy at the top of the lighthouse there are two side-by-side panels of the shootings.
The several breakdowns in the manga. Mayu crying for her father to stop, when Unknown Man tries to rape her and Nana crying over her dad.
Several minor characters get harsh or sad send offs. Kisaragi is introduced in the first chapter/episode, as a clumsy, somewhat ditsy secretary. When confronted with Lucy, she is about to be killed, and hopes her death will be noble, Lucy proceeds to rip off her head and use her as a human shield.
Saito was a scientist at the research facility, who is one of the few people to actually like Mariko, as she acts as a mother to her, even though they've never met and communicate over a speaker. When she finally meets Mariko, she is delighted, but Mariko rejects her, and rips her in half. Saitou's last act is to detonate a bomb in her "daughter's" arm (placed there incase she goes homicidal), stopping her from killing everyone. She dies feeling betrayed by what she thought of as a daughter.
But in Saito's case, the manga reveals she played with Mariko's head, telling her *neither* of her birth parents loved or wanted her. Certainly, this was a lie in Hiromi's case, and Kurama, his initial intent aside, was kept away from Mariko, the very reason for his 'adoption' of Nana.
Saitou's death is indeed subject to debate (Not as much in the anime, where the love was more unconditional). She did manipulate Mariko, but she did seem happy to finally see her, and said she liked her as a daughter. She isn't elaborated on enough for us to know if she was lying about that.
Isobe, Kurama's assistant, is portrayed as reserved about his work, and trying to apply morals, when he is sent as Mariko's caretaker, he controls the bombs in her limbs (which he sees as excessive, cruel, and won't stop the girl). She rips off his arm in a rage, but then reveals that she regrets her life of being locked away, and cruelly treated. As she is about to die, Isobe tells her the codes to stall the bombs, wanting her to live. She thanks him, calls him a fool, and reveals that she was joking, and will just keep killing, as Isobe realizes this, he gets decapitated.
In the anime, he was just a cruel scientist who didn't appear as much, and had more of a Karmic Death. In this respect, he's the reverse of Saito, the other main scientist Mariko killed and who was sympathetic in the anime but less so the manga.
Shirakawa she was a scientist who worked in the facility and was subordinate to Kurama. In reality, she's a spy sent by the government (before the Agent), and is in love with Kurama. She collects data on Kakuzawa, and sends Mariko after Lucy, placing the bombs on her. She does this because she feels that if Mariko dies, Kurama will lose his old life and go to her (in addition to Mariko being, well, Ax Craxy and murderous). Her spying is found out, and she is quite graphically raped by the Director in a scene that comes right out of no where. In the end, she goes to assist Kurama, and tries to save Mariko from Lucy. Lucy decapitates her. Her death wasn't entirely meaningless, her death (along with Isobe and Kisaragi) finally motivated Kurama to just kill Lucy. In addition, her data was enough for the government to recognize Kakuzawa's plan and deploy the Agent.
This was tragic because of the (not entirely deserved) Humiliation Conga she suffers, and her death being so unceremonious
The Agent she breaks into the laboratory, as all of the clones are rising up and killing everyone. She rescues the only living scientist, Arakawa, and saves her from the still functional Mariko clone who had just been released from mind control (the last one released killed Nousou, another scientist). She fights through several clones, running out of room, ammo and hope, and gets to the roof, opting to send Arakawa down a workman pulley. She stays at the roof to operate the controls, sacrificing herself to save Arakawa, in the hopes that she can cure the virus. The Agent just slumps against a wall as the clones surrounding her, dropping her stoic demeanor, and crying, fearing the end, as they execute her.
She survives, as the ground gives way, and she falls into an underground passage, still alive. It's notable in that she isn't an important character, and doesn't even have a name, but she still survived in a series where Anyone Can Die.
The closing theme of the anime. It's a very cheerful song about unrequited love.
Toward the end of the manga, the entire ordeal of Lucy's mother. She had her infant daughter taken from her and abandoned somewhere by her husband, he didn't tell her where she was, she searched for her tirelessly over the years, and eventually she was captured and forced to repeatedly give birth to more diclonius children (most of whom died) until she finally killed herself. Even worse, Lucy completely hated her mother until she found out what happened to her.
During Lucy's horrifying death struggle. After overusing her vectors her body starts to melt. She then says her tearful goodbye to Kouta, while a jacket hides her true condition. But then the 'real Lucy' (or rather the persona representing her instinctive desire to exterminate the human race) takes over and starts using her vectors in an attempt to take the entire world with her. Apparations of Kaede and Nyuu appear and beg Kouta to bring an end to them. Despite this, Kouta can't bring himself to murder her and drops the gun he meant to use. Cut to a bright sky as the strike Kouta expected never came. Instead we see what's left of Lucy handing him the gun, all the while moaning about being in pain. A being filled with hatred and the desire to kill was reduced to such agony (her ribcage is visible) that she begs the thing she hates the most for death.
When it is revealed that barely any Diclonii survived the war, that humans for the most part succeeded in what the facility set out to do, and that while as the human race that caused them such agony will recover and continue to grow, the Diclonius race itself is for all intents and purposes totally extinct, and that there will be no more Diclonii.
Even the anime's opening is depressing. Pictures based off of Gustav Klimit's artwork, showing Lucy/Nyu both in moments of crying and moments of content, perfectly demonstrating the character's journey of pain and suffering in search for a place to belong in the world. Coupled with the amazing song, Lilium, if the opening itself is enough to make your emotions waver, then you know that you're in for something big.
The end of episode 4 in the anime with Nana's presumed death. The poor girl is lying there on the operation table, supposedly waiting for medical attention but really about to be killed. And her father figure Kurama opts to give her the lethal injection personally. Que Nana saying goodbye to Kurama without a hint of anger, clearly aware of what awaits her. And then there's the male chorus version (perhaps even more powerful at bringing out the sorrow of the moment than the One-Woman Wail version) of the opening song playing in the background. It's bound to tear at your heartstrings the first time you see that.
Mayu's past. When she runs away and cries out loudly, kneeling down because of the pain, lonely, at the middle of the night...