Johan's life's work and goal can be chalked down to the perfect suicide. Unfortunately, he feels it necessary to take the world with him...
And Johan is also an expert at driving perfectly sane and normal people to suicide through total Mind Rape. And he does it a lot.
Yuria, Kenshiro's fiancee of Fist of the North Star, throws herself off a building after witnessing the atrocities committed in her name by Shin (who had taken her away from Kenshiro), aided and abetted by Shin declaring that with the current Southern Cross burning down, he'll build a new one bigger and better than the last, which Yuria sees as an excuse for more death and destruction and in HER name to boot. Later on, Shin himself throws himself off of the very same building as a point of pride after Kenshiro mortally wounds him, intending to die from the impact, before the Kenshiro-inflicted mortal wound. In Yuria's case, however, she survived. Only for us to learn she's dying of radiation poisoning anyway. Well, at least she gets to spend her last days with Kenshiro...
After being part of a genocidal slaughter, Roy Mustang felt so guilty over the horrors he participated in that he tried to commit suicide by eating his gun right on the spot, but was stopped from pulling the trigger by his best friend Maes Hughes (his mentor, Dr. Marcoh, in the first anime).
In the manga, Riza threatens to kill Roy when it looks like he's going off the deep end. He asks what she will do when he's dead, and she admits she plans to kill herself, since there will be nothing left for her to live for. That's enough to convince Roy to step down.
Moments after the above, Envy ends his own life by destroying his own Philosopher's Stone to avoid what he perceives as the ultimate humiliation: being beaten and actually pitied by lowly humans.
In the last episode of Gravitation, Eiri Yuki, after remembering his troubled past, is about to pull the trigger on his life when Shuichi arrives in the nick of time.
Mai-HiME has two: Yukariko Sanada prefers to kill herself and her love interest Ishigami, rather than killing the main character and Natsuki kills herself and Shizuru, since they're each other's Most Valuable Persons and the death of one of them would trigger the other's as well.
The first happened in an early episode, when Ashura, disheartened after still another defeat, thought the only way to redeem himself/herself to Hell's eyes was by comitting suicide. Hell rebuked that was dumb, and the way to atone for his/her failures was going on fighting until destroying their enemy.
The second time happened in episode 39, when he was so badly frightened on the possibility of Count Brocken replacing him that he staked his life on his next operation. When he failed, Brocken was all but ordering him killing himself, and he was about to do so when Hell stopped him, stating that even if he had failed in destroying Mazinger-Z, his war tactics had delivered a huge blow to Japan, and he forgave him.
The third -and final- time happened in episode 78. Ashura was so sick of being defeated, mocked and scorned by enemies and allies alike he hijacked the flying fortress Ghoul to crash it against the Institute in a Taking You with Me tactic. He failed, but he died believing he had finally won.
Count Cain: In volume 2, Emile allows himself to fall off the roof of his mansion to his death because he feels guilty for having a "filthy" soul and doesn't want to tarnish his stepsister Lukia, who he loved more than anyone. Cain tried to save him, and probably would have succeeded, had it not been for the intervention of Big Bad Alexis.
Played completely for laughs in Sayonara, Zetsubou-Sensei where the main character, a teacher (on the main page), tries to commit suicide because of every minor thing that happens to him, usually more than Once an Episode. He even has a book with names of people who might join him and tries to get his pupils to sign up.
Said teacher will always fail by being COMPLETELY invulnerable in the long run. He's even survived having his name written in the Death Note.
Skyhigh has Kino-shita, assisted suicide. Normally suicide gets you sent to hell immediately - Izuko says it's murdering yourself - so she researched this technicality and convinced her friend to do it.
Welcome to the N.H.K. has every major character except Yamazaki attempt suicide at least once, always by jumping off a cliff. Sato has TWO suicide attempts. He doesn't want to commit suicide initially either time, and the second he starts out trying to stop his friend's suicide attempt. Incidentally, he does get off the cliff the second time. He doesn't die due to a metal grating that was installed to prevent suicides at that particular cliff.
In the Crashtown Arc of Yu-Gi-Oh! 5D's, (a Darker and Edgier arc of an already darker part of the franchise) Kalin planned to kill himself in the dyne mines after losing to Yusei, unable to forgive himself for his actions as a Dark Signer. (Changed in the dub, of course, where he simply wanted to be sent there as punishment.) Yusei convinced him not to after his loss caused Lotten to take over the place and rule it like a tyrant.
As the Bittersweet Ending to one episode ofYu-Gi-Oh! ARC-V. Dennis is defeated by Kaito, and tells the heroes where they can find the kidnapped Ruri and Rin. Despite being offered a chance at redemption by joining the good guys, Dennis feels that he doesn't deserve to come back after his betrayal. Instead, he decides to do his final performance: jumping off the boat and carding himself.
In Detective School Q, RyuAmakusa seriously ponders suicide after being told by Anubis, the sub-leader of the criminal organization (Pluto/Meiousei) he reluctantly belongs to, that there's no way he can escape from them. It doesn't help that he was almost killed by another Meiousei member when he attempted to save his partner and best friend, Kyuu Renjou from them. He's standing next to a bridge and is going to jump off, but Kyuu appears and talks to him, which makes Ryu swear off suicide.
In another episode, a secretary who had recurred to Pluto/Meiousei to get revenge on the death of her lover at the hands of her evil bosses whips out a knife after being unmasked as the assassin, saying she had planned to kill herself from the beginning so she could be reunited with her lover. Anubis attempts to brainwash the woman into killing the DDS team instead, but she's stopped just in time.
Princess Serenity in the manga killed herself in a past life after the Big Bad offed her fiance. She also succeeded at a Murder-Suicide on a Brainwashed and Crazy Tuxedo Mask, but was brought back to life by the other sailor soldiers who sacrificed their own lives to do it.
In the anime, Bertier tries to use all of her power to freeze herself and Mercury after two of her sisters taunt her and claim they'll take the credit regardless of if she lives or not. Subverted in that her other sister Koan (who's now a normal human) convinces her she's still loved and allows Sailor Moon to purify her and let her become human as well.
Chika Ogiue in Genshiken tried to throw herself off the roof of her old school after her "friends" severely traumatized a boy she liked by showing him extremely graphic drawings she'd made of him. She survived. She ends up with the Genshiken after hurling herself out a window following a fight with the Manga Club, as well (ending up with a broken arm), and at one point has to be stopped from doing it again by Saki. It's a Running Gag that she will jump out of the nearest window when she seems to be losing an argument.
Princess Tutu has at least two main characters consider suicide during the show. Also, an early episode about a Wili Maiden states that she is the ghost of a woman who committed suicide when she was betrayed by her love.
Noboru Yoshikawa attempts suicide by jumping off the school building twice because of his unceasing torment bordering on sexual abuse at the hands of Anko Uehara. As is usually the case, Onizuka helped him through it both times.
Henrietta clearly exhibited suicidal tendencies before her conversion, after having her parents killed in front of her and being repeatedly raped near their corpses.
Elsa killed her handler then herself prior to the manga beginning.
This is Petra's backstory. She was a talented ballerina who developed cancer in her leg. In order to save her, her leg was amputated. Being unable to live without dancing she attempts to kill herself but survives. At the end of the manga it's shown her cancer came back as leukemia and she dies... Though so do all the other cyborgs, and in comparison to most her death was rather peaceful.
Most people who reach the final stage of Hinamizawa Syndrome die by clawing out their own throats - including Keiichi in Onikakushi-hen, Tomitake in every arc except Matsuribayashi-hen, and attempted by Satoshi in the backstory, though he was stopped. Also, Natsumi does this in Someutsushi-hen.
There are also several other deaths which appear to be Driven to Suicide, but turn out to be murder: Rika's mother in the backstory (seen to be murder in Matsuribayashi-hen) and Dr. Irie in Tatarigorshi-hen (seen to be murder in Minagoroshi-hen).
After the events of Tatarigoroshi-hen, Keiichi is driven to suicide in what is implied to be a different manner, since he was stopped and sent to a mental institution. Hey, if you'd just managed to curse death upon your entire village successfully after being shoved off a bridge by your adopted sister, you might go a little nuts too.
His God complex. He thought he was a God, due to everyone he said he wished dead, died. Coincidentally.
Shion does the same thing as Keiichi in Tatarigoroshi-hen (and, implicitly, most other arcs with the exception of the "real" Tsumihoroboshi-hen, where everyone died in the school explosion, rather than the gas disaster), according to the victim roll. The only difference is that she isn't stopped. Not sure whether it's similar to what happened in Watanagashi-hen/Meakashi-hen, however. Although she wasn't implied to have had an episode of Hinamizawa Syndrome at the time, she could have easily been in the second wave of cases that Onisarashi-hen explores.
Rena, in every world, minus the "good" world. However, it's an attempted suicide prior to the series. She attempted to slit either her neck or wrists (depending on the medium) after a depression but was caught before she bled out. She gets better, usually.
One particularly cruel version of this trope happens in Fushigi Yuugi. Chiriko, the Teen Genius of the Suzaku Seishi, is possessed by the evil priest Miboshi from the Seiryuu Seishi, and the only way to exorcise him was committing suicide and killing both of them in the process. Chiriko did this by stabbing himself to death, despite his friends' pleas to stop.
On their way to Taiitsu-kun's place, Miaka is trapped in a mirror and the "Mirror World Miaka" takes her place. The other Miaka admits all of her inner-kept feelings and thoughts, taunts Miaka and ends up torturing Tamahome and Hotohori. Miaka quickly figures out that the only way to get rid of the other Miaka is to commit suicide, and she stabs herself in the chest with a plate shard. She got better.
There's some attempted suicides from other characters before that, too. Most notably, Yui tries to slit her wrists because she believes that she was gang raped and that Miaka had abandoned her to that fate... even though both of those reasons are lies fed to her by Nakago in order to turn her against her friend.
And finally, in the series Miaka tries to drown herself when Tamahome was Brainwashed and Crazy. Hotohori had to dive in and save her.
Also in the 3rd OVA, Mayo attempts to drown herself in that pond when she realizes what a psycho bitch she had been and that she's nearly destroyed the world just to get Tamahome. Much to the Fan Dumb's dismay, Tamahome goes in after her and brings her back, allowing her to Must Make Amends and save the Universe of the Four Gods.
Played with in Re:Zero. In one time loop, Subaru successfully manages to survive his fourth night as Roswaal's mansion, but Rem dies instead. After Ram initiates a Roaring Rampage of Revenge against him, believing he's responsible (or at least, that he knows more than he's letting on), Subaru flees from the ground and contemplates throwing himself off a high cliff. Eventually he does so, but only so he can reset the timeline and fix things, not because he's given up.
At least he doesn't get all angsty about it. The only time he actively tried to kill himself was when he used his Gundam's self destruct, but that was only because it seemed at the time that he had failed his mission. The other times, he was "just" a Death Seeker.
Narutaru has Akira Sakura, a cripplingly shy and depressed girl who is seen tentatively taking a razor blade to her wrist in the first episode/chapter she appears in, and later grabs a soldier's gun and points it to her own head. Eventually, in the manga, it appears that she does kill herself by throwing herself out of a hospital window onto the street below. Given what happens to all the other major characters, she probably got the closest thing to a 'happy' ending out of anyone.
It's implied that Shinji and Asuka attempt suicide, though the suicide is implied rather than explicitly shown. Asuka is found naked and barely conscious in a bathtub with what may be slit wrists, and Shinji is shown at the beginning of End of Evangelion clearly dampened from an attempted drowning.
Naoko Akagi dies of a fall from the top of the MAGI superstructure. It's strongly implied that she threw herself off the bridge after learning that Gendo didn't love her and murdering Rei.
Shinichi/Conan himself tried his best to avoid driving criminals to suicide after Pulling The Thread on the criminal; the only failure being Seiji/Narumi of the Moonlight Sonata case, above.
An episode of Paranoia Agent deals with a group of friends online making a suicide pact... only for the two men in the group to respond in horror when they find out the third member of their group is really a young elementary school girl. They spend the rest of the episode trying to shake the girl and foil her suicide attempts, while succeeding in their attempts, only to fail in increasingly bizarre ways. In the end of the episode, it turns out they all died during the men's first attempt, and their attempts afterwards have been failing because they're ghosts and already dead. It probably says a lot about the series that this is actually one of the most lighthearted episodes in the entire series.
Mahou Sensei Negima!: Yue seems to be like this after finding herself in a love triangle with her best friend and Negi; she feels like she's betrayed her friend and jumps off a waterfall. Subverted as it turns out she had a grappling hook. Double subverted when the grappling hook breaks. Triple subverted when it turns out that when the grappling hook breaks, she was close enough to the bottom to land without injury.
Because Kids Are Cruel, Flame of Recca's Kaoru Koganei attempts to slit his wrists. He was stopped by Kurei (whom Kaoru would eventually come to see as an older brother), but still cut deep enough to leave a scar on one wrist.
In the manga, those who kill themselves become Shinigami. There is some debate as to whether this is a a punishment or not.
In the anime Mitsuki attempts suicide twice. Once she tries sleeping out in the snow on Eichi's grave so she could join him in death. And a second time she tries jumping off the hospital roof. Only to be rescued by Takuto.
Eugene in Hanasakeru Seishounen, bonus points for the fact that he wanted to die the same age as his mother committed suicide due to a complicated revenge plot on the part of Volkan. Eugene's suicide is averted, though, by Kajika. At the beginning, they find out that he has driven at least three women to suicide.
A very tragic example of an already tragic trope from from Let Dai, in a terribly ironic fashion: Eunhyung. After much sorrow from being gang raped and becoming utterly alienated from the world at large she finally begins to recover, rumors at school and eavesdropping on the boy she likes confessing his love for her sister finally take her to the edge. Ironically, said boy then goes to correct this assertion and expresses his love to Eunhyung who no longer hears this part of the conversation. To make matters even more painful, the boy makes a public confession via a banner that he hangs at her school... only to be informed that she committed suicide the day before. A true Tear Jerker moment.
Mobile Suit Gundam ZZ. Haman Karn's entire Neo Zeon regime collapses when an uprising from within her own ranks results in the mutual annihilation of both factions, effectively crushing her ambitions for dominion over Side 3 and the political influence it enabled her to exert on the Earth Sphere. In addition, the only people she's ever shown interest in reject her. Haman essentially loses everything she?s ever valued or hoped for, and being left with no better option available to her, she chooses to just put an end to her misery.
Mobile Suit Gundam 0083: Stardust Memory. Kou gets court-martialed for stealing the GP-03 after the GP-01 gets destroyed, but is released after Captain Synapse commits suicide to take responsibility for it.
Chaos;Head. Takumi in the penultimate chapter of the game; first by wandering into Yamanote Doori traffic, then by hanging himself in his apartment. Considering that he'd just found out he doesn't exist, all his memories after the age of 12 are fake, he is in fact a delusionary existence created by himself (the real, wheelchair-bound, terminally ill one), and that Rimi, the only human being he cares about, knew all of this all along (and has abandoned him after telling him all this), it's hard to blame him. Later, he gets better... just in time for everything to really go to hell.
Soichiro Yagami does this in a more traditional manner, considering suicide and eventually committing suicide by Mello.
In a rare good character example, a minor ally in Fang of the Sun Dougram commits suicide on screen by shooting his brains out.
In Saikano, the scientist who made Chise what she is eventually comes face to face with the consequences of his work. He shoots himself to death.
Yukio Washimine in Black Lagoon, who commits jigai with the also deceased Ginji's trusty katana at the end of the Fujiyama Gangsta Paradise arc.
In a particularly tense scene in GITS: Solid State Society, Togusa is ghost-hacked by the Puppeteer and forced to take his daughter to the hospital, where the Puppeteer informs Togusa that she will be given a cybernetic body so she too can be kidnapped, whereupon Togusa's memory of ever having a daughter will be wiped. The Puppeteer then releases Togusa's gun arm, giving him the option of committing suicide instead. Fortunately the Major has been tracking Togusa the whole time and is able to save him.
Shiori and Sayuri in Kanon. The former believes she has a month left to live, and her sister, perhaps the only person she has been living for, rejects her. The latter was destroyed by guilt when she believed that the way she treated her baby brother led to him dying of a terminal illness. Neither manages to go through with it.
In Akumetsu chapter 32, one of the bankers spared by Akumetsu decides to commit suicide rather than face up to Akumetsu's demands.
Kotaroh of Pita-Ten does so rather than lose Misha when she is forced to return to heaven.
X eggs in Shugo Chara! happens when they have too much stress to unable to handle it, they break themselves which sends waves of sadness the X eggs have stored in them.
In D Grayman, main protagonist Allen Walker attempts to slit his own throat in order to stop his Innocence from harming someone who was having an And Then John Was a Zombie moment. While the attempt was quickly interrupted, it gives a whole new grim meaning to Allen's earlier promise that he would stop The 14th if he attacked the Order.
In Sakura Gari both Masataka (neck piercing with a knife) and Souma (slitting his wrists and then placing his arms in a bath tub) either consider or attempt to kill themselves but fail. Souma's sister Sakurako successfully manages to commit suicide in chapter 9, slitting her wrists open (apparenrly with the family's katana) and then drowning herself in a nearby pond.
In chapter two of Gunjo the women run into a lady who wants to kill herself out of guilt for the death of her son.
In the first few chapters of Bakuman。, Mashiro Moritaka thinks his uncle Mashiro "Kawaguchi Taro" Nobuhiro, who was said to have died from overworking himself, committed suicide because he was unable to follow up on his successful manga series with another one, and was deep in debt. After going to his uncle's studio and seeing the effort he put into making submissions (as the editor in chief of Shonen Jump points out, he submitted one five days before his death), he realizes that his uncle had never given up, making this a subversion.
Chapter 38 of Franken Fran begins with a student, despondent from a lifetime of bullying, jumping off of a building. The plot of the chapter begins when he lands... on Fran.
In the Romantic Trilogy Super Robot series (Combattler V, Voltes V and Daimos), all the dragons in their respective series chose to end their lives; one of them for not having any more reason to live and the only option left is to die in an obviously unwinnable battle as the Proud Warrior Race Guy that he is; and the othertwo for deciding that they have given the people around them too much grief and suffering to even have a right to continue living.
Tohma of Magical Record Lyrical Nanoha Force, upon realizing that the events of the series had turned him into someone who could only live if he constantly kills other people, jumped off the spaceship he was in, hoping that he could end his life before his out-of-control powers could kill the people he cares about. Unfortunately, his Superpowered Evil Side had other ideas.
In Holyland, Yuu wanted to commit suicide in the backstory but could not bring himself to take the step when he was actually at the rooftop. Masaki has scars on his wrist from an attempt; we later learn that he would have successfully bled out if Mai had not walked in on him.
And then there's the cute scene in Windaria where the starcrossed lovers, Princess Ahnas and Prince Jihl meet in the forest for a romantic rendezvous. The Princess playfully steals the Prince's handgun in their game of tag, ending with the two in a sweet embrace when he retrieves it. Fast forward then, as Jihl's Father plunges the the two countries into a brutal and very bloody war, in which honor and duty forces the lovers to face each other commanding opposite sides ... ... where Princess Ahnas, seeing no other way out, in a desperate attempt to end the conflict, offers to meet her beloved off the battlefield. In one of anime's best, most under-appreciated and most heartbreaking scenes Ahnas and Jihl meet ... they embrace ... the Prince shudders, his eyes go dull and he falls. For, once again, Ahnas had stolen his handgun. She places the barrel to her temple, closes her eyes, and then pulls the trigger.
In the Eureka Seven movie, Eureka shared her story to Renton of her 8 years under the military imprisonment. Apparently the torture is so great that the thought of suicide crossed Eureka's mind several times but her desire and love for Renton motivated her to survive.
In Descendants of Darkness, Tsuzuki succeeded with this when he was a human, and a while later he became a Shinigami. (Which explains why he angsts/wangsts so much about his work). Later, he tries to comit suicide again thanks to Muraki, and Hisoka has to hug him and beg him to not do so.
Black Paradox is a manga about 4 people gathering together to commit a group suicide. Creepy things happen instead.
Kakashi Hatake's father, Sakumo Hatake, deserves mentioning. He and his team were sent on an important mission for Konoha. When his comrades were in danger, Sakumo chose to abandon the mission and save them. The mission's failure was a big blow to the village, and consequently everyone came to hate Sakumo, even the ninjas he saved. Sakumo fell into a deep depression, soon dropping training and his skills altogether before he committed suicide.
The anime filler suggests his son Kakashi was suicidal himself, both as a child and later in his life before he got Team 7, with Kurenai saying he fought like he 'was eager to die', not to mention 13 year old Kakashi walking around with a book titled 'How a shinobi should die'. Given his family history, this is some scary stuff. Fortunately getting team 7 did him a whole world of good.
Madara was aware this was a possible outcome of his Despair Gambit on Obito. As he needed the latter alive, he averted this trope by placing a seal on Obito to prevent suicide.
The manga version of the Trigun flashback arc, which reveals to us the background of both Vash and Big BadKnives, with Freudian Excuse and a side of showing what the crap is up with the setting, features this. From Vash 'I disapprove of suicide more than anything' the Stampede himself, no less, and twice. Contains a heavy helping of Better to Die than Be Killed, and a lot of disillusionment.
First, the twins lock themselves in the lab where they found out about Tesla for a week without food or water, with apparent intent to die, and then after Rem has broken in while they were unconscious and nursed them back to health, Vash wakes up and goes for the knife she's using to peel fruit. He got better.
A Pokemon does it in the manga The Electric Tale of Pikachu. It was the "Black Fog", a giant evil Haunter. It was so proud it preferred death to being captured.
Mitsumi from Pokémon: Diamond and Pearl Adventure!. She decides to stay inside the Team Galactic HQ even though it's collapsing, saying that she won't be haunted by her past. Luckily Jun comes in and saves her.
Played for Laughs during the Enies Lobby arc. One member of CP9, Kumadori, will attempt to commit seppuku when someone else on the team screws up. The problem is, he instinctively calls up his rokuskiki power of "Tekkai", which hardens his body so he can't stab himself. He then blubbers dramatically about how he can't die.
In Oniisama e..., Rei, Fukiko, Mariko and Aya all either contemplate or attempt to do this to varying degrees, but ultimately fail. In the manga, Rei actually does commit suicide, by overdosing herself with pills. In the anime, however, she dies in an accident. And in Rei's backstory, her mother commits suicide by drowning herself in the ocean.
In Revolutionary Girl Utena episode 37, Anthy tries to commit suicide by throwing herself off of a building. Fortunately, Utena saves her.
Suicide Island: This trope is naturally a big topic in this story. People who attempted suicide will be dropped off on this island if they consent to it, and be declared Un Persons. The story examines why the characters experienced this trope. For some, it was a due to the Crapsack World they're living in. One character, Kai, who seemed so rational and went into therapy along with Sei, says that he failed, which was why this happened to him. Sei himself is pretty complicated. He started out as a Loners Are Freaks type, but he formed a bond with a young woman and member of the archery club, Eiko-senpai. However, her suicide apparently drove him to Hikikomori levels and then to this trope. Eiko-senpai's suicide was apparently over the fact that she had sex with her sensei, the head of the archery club, and got pregnant from this. The guy was leaving the club and getting married, and when she tried to turn to sensei for help, he refused (Jerkass), which apparently put her in a bad spot. Ouch!
In the classic manga Natsu E No Tobira, a schoolboy named Claude commits suicide after being rejected by a boy he liked. Said boy is The Protagonist, Marion, who heavily blames himself when he finds out.
Toward the end of the Area 88 manga, Saki admits that the Asranian people will not accept him after his role in the civil war. After carrying Abdael's dead body into Soria's tomb, Saki shoots himself.
In Pandora Hearts, Alice's death is initially set up to make Vincent look like the murderer. Turns out, in a combination of this trope and Heroic Sacrifice, Alice killed herself with the shears after wounding Jack with them in order to keep him from continuing to use and torture Oz by having him kill people. Killing herself kept Jack from being able to contact her twin sister in the Abyss, who was lonely and wanted Jack to bring the world into the Abyss so that she could be with him.
In A Cruel God Reigns , Jeremy throws himself into the lake in Lynn Forest after finding out that his mother knew that he was being raped by his stepfather, but did nothing. He also attempts to asphyxiate himself with a gas oven after returning to Boston to live with his Aunt Karen. Jeremy contemplates jumping in front of an oncoming train and tries twice to commit Murder-Suicide by steering the wheel of his stepfather's car into traffic, but is unsuccessful both times.
One member of a small guild takes the guild's savings to buy a house. While they're waiting, the rest of the guild decides to go on a quick dungeon delve to pass the time. They walk into a trap and are all killed—except for Kirito, who was hiding the fact that he was twice the level of everyone else. When he tells the survivor what happened, said survivor immediately jumps off the nearest balcony.
When the front-line group is preparing to take on the floor 75 boss (a boss who already killed ten scouts), Kirito tries to get Asuna to stay behind so she'll be safe. She flat-out tells him that if he dies, she'll kill herself, so it will give them both a better chance to survive if they go together. It helps that she's only about a half-step weaker than him.
When Kirito has to fight a one-on-one duel with Akihiko Kayaba, Kirito requests that if he loses, that his opponent keep Asuna from killing herself. Asuna ends up Taking the Bullet for Kirito, but apparently Kayaba interpreted "keep her from killing herself" as "if she dies, stick her in a waiting room rather than microwaving her brain immediately," so when Kirito wins the game moments later, they are both saved.
In the first, Casca, feeling that she has failed Griffith and the Hawks, tries to throw herself off a cliff, only for Guts to pull her back at the last minute.
A rather crueller version happens to Griffith, when he tries to impale himself on a rock following a years worth of Cold-Blooded Torture, only to fail.
Prince Fay of Valeria does this in Tsubasa -RESERVoir CHRoNiCLE-. After years spent in a tower for the sin of being born, he finally breaks and declares that he wants to die. Fei Wang Reed then conveniently shows up and offers to free Yuui in exchange for Fay's life. Fay takes him up on this offer.
Prince Yuui - the twin that survived, the Fai we know - as well. After he stabbed Sakura because his curse activated he was only a sword swipe away from killing himself after killing the other two as well but Kurogane stopped him. If not he would have committed suicide. Sakura knew this and tried to change it which resulted in this.
This is Moeka's backstory in Steins;Gate; due to her social phobia, she believed herself worthless and was about to jump from a building when she got a message from someone named "FB" recruiting Rounders (i.e., hired guns) for SERN.
This is the plot of the first story in Confidential Confessions. Two high school girls befriend each other due to their shared desire to die. One is bullied by girls, another has an abusive father. "Asparagus" does end up committing suicide in the end
In Fruits Basket, Kyo's mom commits suicide - most people assumed that it was because of Kyo himself, but it's later revealed that it had more to do with her abusive husband.
Ghost Talkers Daydream features 11 suicide cases between chapters 3 and 17, most of which were orchestrated by Yuo, through the "Rock & Roll BBS Suicide" website. The crux of the series, however, reveloves around Misaki and the Tokyo Metropolitan Police trying to find the site of "The Flame of Lament"note a planned reinactmenet (by Yuo's followers) of a protest by a group of Buddhists priests against the Japanese government, by mass immolation to prevent it from taking place.
Girls Go Around reveals that the events are a time loop created by Chihiro because Kyousuke committed suicide on graduation day in their third year. She creates the time loop in hopes of getting him to open up, make friends, memories and enjoy high school life... turns out, one of the girls will die on graduation day and, after going through several time loops himself to save them, Kyousuke figured that if he can't save them all, but won't abandon them, he choose to kill himself so they can live. Needless to say, that's not okay with Chihiro, but...
Durarara!! has the Day In The Limelight episode for Rio Kamichika, a depressed highschooler who feels severe anguish after discovering that her father's cheating on her mother and her mother presumably not caring even after finding out. After making a suicide pact with an online friend called Nakura, Rio meets him in person on a rooftop. Unfortunately, "Nakura" is actually Izaya Orihara, the Big Bad and a truly Manipulative Bastard. He has some very choice words for Rio and after leaving, accusing her of being a boring person with no actual desire to jump as he leaves, watches with a smirk as she jumps off the building. Fortunately she is rescued by Celty Sturlson who explains her reasons by telling Rio "the world isn't as bad as you think." Rio begins thinking of the deceitful way life is in a different light after this. Right before being Demoted to Extra.
In Claudine, the titular character Claudine does this by shooting himself in the middle of a snowy night after he finds out his last lover Sirene chooses to be with his brother Andre.
Rayet from Aldnoah.Zero tries to shoot herself after revealing she's half-Martian and almost killing Princess Asselyum. She's stopped though.
Being such a cynical series, Oyasumi Punpun is filled to the brim with this:
Aiko hangs herself in the final chapters.
Punpun's mom tried to kill herself and Punpun. Her husband caught her but Punpun saw it and thought he was abusing her. This caused his dad to become arrested at the start of the manga.
Punpun himself is very depressed and suicidal for much of the manga. He expresses wants and plans to kill himself several times. He stabs himself in the eye at the end of the manga but survives. He loses his eye..
Chiyuki, aka the nameless protagonist of the series, killed herself due to self-loathing and depression after she becomes unable to ice-skate anymore after a knee injury.
Yousuke in episode 4 commited suicide due to family issues. It was a random decision and he regretted it in Quindecim.
One of Harada's girlfriends killed herself after he broke up with her. Her sister killed him in revenge.
Mayu tries sacrificing herself for Harada however everyone is Dead All Along and the trap was fake.
Subverted in Unlimited Fafnir. Iris seriously contemplates jumping off the school roof to avoid turning into a dragon against her will during episode 2. Fortunately she's too scared to actually follow through, and Yuu helps reassure her that he'll protect her.
Manami tried to jump in front of a train after her boyfriend dumped her but Ayumu saved her. It's left vague if she was serious or not. She's a Manipulative Bastard who later bullied Ayumu into attempting suicide, so that could have either been a 'game' or her Start of Darkness.
Ayumu tries to jump in front of a car due to depression and being severely bullied. Luckily Hatori stops her and that is where their friendship starts.
To avoid Manami's bullying a girl jumped from a school balcony. She survived but ended up in the hospital.
Kurumi finds a boy who hanged himself due to the Zombie Apocalypse. She calls him "cowardly" because he preferred to die than try and survive.
Kurumi wanting to keep a gun around, supposedly for killing zombies, is implied to be more for incase she decides to kill herself. The gun is thrown away because it's decided that a gun would be more danger to them than zombies (as no one is trained in gun safety).
The characters try to meet a survivor who is using a radio to tell people where she is. They're too late and when they arrive they find her locked in a closet, already a zombie. She wrote a letter saying she would try to kill herself but if she failed not to open the closet.
The protagonist Shouya was going to kill himself after making amends with the girl he bullied in elementary. He eventually decides not to and his mother gives him a good calling out when she realizes his plans.
Shouko is revealed to have been suicidal due to Shouya's precious bullying. Years later she attempts suicide after a festival however Shouya saves her. He ends up falling into a body of water and ends up in a coma.
In ReLIFE this is revealed to be why Kaizaki left his job. His senpai killed herself after being treated horribly by the rest of the company.
Ken Kaneki admits to himself that his duel with Arima at the finale of the original series was a failed suicide attempt. He wasn't able to "die properly", and after regaining his memories in the sequel... he decides to "die in style". Over the next several months, he isolates himself from those that care about him and places himself into a position of authority within the CCG. This is all leading up to betraying his superiors during a critical mission, arranging a prison break with a two-part Self-Sacrifice Scheme at it's core. After rescuing Hinami, he intends to goad Arima into killing him once and for all. It doesn't end as he planned, with Arima repeatedly wounding him while goading him to fight harder. A hallucination of his childhood friend, Hide, makes him realize his own conflicted feelings over dying and resolve to go on living in spite the pain.
In the same vein, Kishou Arima turns out to be a Death Seeker secretly plotting to groom a successor to kill him and lead a revolution against the Government Conspiracy. When Kaneki refuses to finish him off, Arima takes matters into his own hands and slits his own throat. Before dying, he confesses that he was Secretly Dying and preferred to simply "speed things up". He requests that Kaneki take the blame for his death, becoming the legendary "One-Eyed King" and a Hope Bringer for ghouls by defeating the "Grim Reaper".
In Kasane, Tanzawa Nina jumps off a roof when she starts to feel like her existence is worthless now that Kasane is playing her "role". Instead of dying, she ends up catatonic - but retains her consciousness -, which only makes matters worse.
Subverted in Angel Beats!. Despite being a Broken Bird who has deep trauma over the fact her younger siblings were killed by robbers when she couldn't find what they were asking for, Yuri insists that her death wasn't due to suicide. It's never shown how she ultimately died though.
Twofer in Attack on Titan—Mikasabecomes dangerously reckless after she believes that Eren is dead; she eventually breaks down and almost allows a Titan to eat her, only to find, to her own surprise, a reflex to fight back at the last second. When Armin finds her, he has every intention of giving her his own gas and staying behind to kill himself before the Titans get him, but Mikasa won't allow it.
In one episode of Osomatsu-san Jyushimatsu falls for a nameless woman. He met the women while he was practicing his batting skills on the beach. The woman stood on a nearby cliff waiting for him to leave so she could jump, but she ended up rescuing him from accidentally drowning. It's never clarified why she was suicidal however it's implied that she had bad experiences working in the AV industry.
When Youtarou from Kurage No Shokudo opens up about his brother's death, it turns out that Youtarou's brother killed himself. Weeks after his death, Youtarou overhears his parents talking about how much they miss him and that looking after Youtarou was too painful. Driven by grief himself, Youtarou ran away from home and attempted to drown himself.