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Tear Jerker: CLANNAD
CLANNAD is where one will laugh and cry with the characters all within one episode
CLANNAD is a Key Visual Arts game, and as such, features many emotional moments across both its seasons. In particular, Nagisa, the female protagonist, is essentially the personification of Tear Jerker in that she's a shy, timid, ill girl from a happy family who is gentle to a fault, gets emotional easily, has unclear ambitions, sings an old children's song that no one appreciates, and occasionally gets so sick that she has to skip a good chunk of school, which leads to her having to stay back a year and leading to the events that follow. While CLANNAD may not have as many Tear Jerkers as other anime, it probably has some of the most poignant ones.
Fuko was lonely for a very good part of her life and just recently got new friends for support. While things looked like they were recovering, her friends' memories of her disappear from her friends' minds more quickly than they appeared and once more left her. Despite this, she nonetheless remains by their side in wait until they could see her again: they eventually do.
Sanae started to forget her after she'd visited Fuko's body in the hospital. What made it worse was that she knew it was happening, and was inconsolable, on the floor, asking through her tears if Fuko was there and if Fuko knew that she'd always be welcome at the Furukawa house. Sanae's reaction parallels that of a recently-blinded person reaching out to someone she knows is there, but cannot see anymore.
Whenever Nagisa is reminded of how she may lose her memory of Fuuko eventually, she holds onto her like a teddy bear.
The morning after their impromptu party with Fuko, Tomoya and Nagisa wake up and wonder what the two of them had been doing the previous evening.
Fuko's arc ends with her sister explaining that Fuko's condition has deteriorated to the point she might never awaken from her coma, potentially causing her to disappear from everyone else's memories.
Tomoya: That girl student suddenly became the talk of the school. Pure and earnest, running around the school... that's the image of the girl. And then we all waited for the day that girl might awaken. I was definitely one of them. And that day will, someday...
Fuko: Please, please be my friend. Be one of my very best friends, would you?
Ichinose Kotomi's backstory. Her first and only friend - and implied crush - was Tomoya. However, as the years went by he'd managed to completely forget about her, and she has become so withdrawn that she initially fails to respond to any human contact (she doesn't even notice when Sunohara tips over a fully-loaded bookshelf to get her attention) with the one exception of Tomoya calling her "Kotomi-chan". As the story develops, we find out that her parents had died in a plane crash when she was a child and she Never Got To Say Goodbye. Upon hearing what happened, she lapses into a Despair Event Horizon, leading to an attempt to burn her house down while she was still inside. The attempt fails thanks to some last minute internvention, but Kotomi's left alone in her grief for years. To add salt to the wound, when she finally finds her childhood crush again, he winds up choosing her newfound best friend Nagisa over her, even though she's been in love with him since she was a very small child.
Kotomi eventually comes to terms with her parents after receiving the Teddy Bear that was to be her birthday gift many years ago and realizes that her parents' last act was to ensure that she received that gift, even at the expense of their own research.
"Father... Mother... Welcome home."
Though not quite as bad as Kotomi's, Nagisa has a reasonable Tear Jerker when she finds out exactly how much her parents have sacrificed for her sake, going into a Despair Event Horizon upon the revelation and publicly breaking down in front of her entire school. Of course, with the Furukawa's being who they are this only leads to a Crowning Moment of Heartwarming.
Yusuke Yoshino's backstory is a gloomy one: he used to be a pop star whose career died after he began to singing about the plight of some terminally ill children...ultimately driving him to drug abuse. It gets worse when you consider that he was driven to drugs specifically BECAUSE he cared.
The ending song, ''Dango Daikazoku'' is fairly happy in actual content but evokes sadness; its significance becomes apparent in ~After Story~ once the viewer sees who sings it to whom. The song makes another return when Tomoya invokes the Reset Button Ending. Subsequently, both Nagisa and Tomoya sing Dango Daikazoku to the newly-born Ushio.
CLANNAD After Story
Misae's arc in Clannad ~After Story~ is a moving one and ends with this exchange:
"I'm sorry I couldn't be with you until the end of the festival."
Episode 16 of ~After Story~, namely, the part where Nagisa dies.
Tomoya desperately crying out her name and all the flashbacks make it even worse.
Episode 17 was equally unbearable. All the cutsie anime antics could barely cover up the fact that Tomoya is still recovering from a Heroic BSOD that lasted five years. That, and his daughter and he are barely speaking to each other, very much like how Tomoya's father emotionally abandoned him after his mother's death.
Episode 18 ends with Tomoya finding himself unable to finish telling the tale of Nagisa to Ushio, breaking down in tears and crying out her name.*
This very moment is pictured above.
In episode 19, Sanae and Akio's conversation reveals the fromer's bottled-up sorrow.
Akio: It's all right, you know? You've done well. Now it's your turn to cry.
Akio: Even with all hope gone, I'll still help you. I'll be here until you stop crying. So it's all right now.
In Tomoya's father's arc, the moment when father and daughter hugged each other for the first time, and when Tomoya was telling Ushio about her mother and starting crying halfway through, quietly repeating "Nagisa..." is a particularly tear-inducing scene.
Dango Daikazoku returns in Episode 20 when Ushio asks: "Daddy, can you sing Mommy's song?"
In Episode 21, Ushio dies in Tomoya's arms from the same sickness that claimed Nagisa. Tomoya dies as well from freezing to death.
Tomoyo's route in the game is unusual in that Tomoya and her hook up quick, luring players into a sense of peace with Tomoyo waking Tomoya, making him lunch, and helping him study in between sessions of sweet nothings and kissing. These times don't last, as the entire student body work towards and succeed in breaking them up. In the aftermath, Tomoya returns to his old ways punctuated with the heart-wrenching line "and now the last thing Tomoyo gave me...is gone."
In the Visual Novel, Kappei's arc has Ryou and Tomoya visiting him in the hospital to convince him to have the operation on his leg. It goes as far as Ryou talking about marrying him and having a family. As touched as he is, when he mourns over the fact of losing it, Ryou's response is simply
"Even if you lose your leg, you'll still have arms to hug me."
Depending on your final option, Fuko whom had possibly woken up at the end of her arc will say something different at the end.
Fuko: If you don't mind, please become Fuko's friends!
Fuko: If you don't mind, please go out with Fuko!
Seemingly as a prelude to the particularly gut-wrenching moments, the song The Place Where Wishes Come True almost always plays in the background. It is first heard in the preview for the next episode at the end of episode eight of the first season, accompanying Fuko's little narration.
Episode 18 of ~After Story~ takes this to a whole new level with a soaring version of that tune when Tomoya and Ushio reconcile. Viewers are suggested to have a box of tissues ready.
To all fathers out there, imagine that your wife died of an unknown illness and your daughter is dying of the same thing in your arms, and the last thing she said was "I love you Daddy". You should be able to relate.