This is based on opinion. Please don't list it on a work's trope example list.
Tear Jerker / Battle Royale
Battle Royale is chock full of Tear Jerkers from beginning to end. One of the most heart wrenching examples occurs when Hiroki Sugimura engages Kazuo Kiriyama in a vicious hand to hand fight that leaves him maimed but victorious...until he remembers that Kiriyama had the kevlar vest and survived the spray of bullets that Sugi used to end the fight. After the touching underdog fight that Hiroki had put up, seeing all of his pain and suffering made pointless was heart breaking, made worse by the cold blooded murder of his love interest in front of his eyes while he is helpless and cursing himself for telling her his feelings. His thoughts during the last moments are unbearable.
The kicker? All he wanted was to protect Kayoko. She dies because she refused to leave him after confessing his feelings for her.
Takako Chigusa's death earlier on, in Hiroki's arms. Doubles as a Crowning Moment Of Heart Warming as she finally confesses her feelings to him, even though she knows he doesn't requite them.
Mitsuko Souma's death in the manga, while being Nausea Fuel at the same time. Especially sadder considering that deep down under the Femme Fatale persona she constructed, she was just a sad little girl who wanted her father just one more time ("Daddy's Girl" indeed).
Her death in the movie is also heartbreakingly sad, especially since, prior to her fight against Kiriyama, her awful childhood was revealed in a flashback. The music during her death does not help. Also, her last thought: "I just didn't want to be a loser anymore".
The Crowning Moment of Heartwarming that Shinji Mimura and Yutaka Seto share is interrupted by Kiriyama, who guns Yutaka down before either of them even know he's there. Mimura then dies slowly, piece by piece, while trying (and ultimately failing) to kill Kiriyama.
Shinji: Unc- Yutaka... Missed the shot... Missed the clutch shot! Saw past him, Kiriyama saw past him... Nothing there, emptiness... Nothing there, Nothi-...
" Shu, I can feel again", proves monsters like Kiriyama sometimes can achieve some sort of peace, even in their last breaths.
Making it worse is what we see him doing before the car accident that took away his ability to feel. What do we see Kiriyama doing as a little boy? Using his brilliance to help people, cheering his little brother up, and goofing around while watching cartoons with his dad like a normal kid. You really get the sense that if it hadn't been for that one accident, Kiriyama would've grown up to be someone both compassionate and brilliant, someone who probably would've had a positive influence on the Crapsack World of the story. Imagine such a person in the game. Most likely, he would've fought back just like Shinji, probably would have succeeded, and plenty more kids could have walked off that island alive along with Shuuya and Noriko.
The scene as he's regaining his emotions gets even worse when you realize that he is actually feeling the pain from his mother's death for the first time. It's so painful for him, he is mentally screaming that he wants to 'go back to the gray' because he can't take the sudden rush of grief. If Shuuya hadn't mortally wounded him moments later, imagine how he would have reacted to the knowledge that he brutally murdered his classmates in cold blood. Almost makes his death seem like a Mercy Kill.
Kazuhiko and Sakura's death, especially in the novel where the chapter is written very peacefully, rather than tense like the rest of the book
Hiroki's death scene together with Kayoko. In the film, Hiroki avoids attacking anyone and instead searches for Kayoko. Unfortunately, when he finally finds her, she is frightened, misunderstands his intentions, and shoots him. Even after she fatally wounds him, his first thought is for her safety as he tells her to run away because someone will be drawn to the gunshots.
I found the following scene where Kayoko realizes what she has done, and lamenting how he didn't tell her earlier sad. Especially considering she doesn't know what to do now. And seconds later, guess what happens? Mitsuko comes out of nowhere, and shoots her in the heart, leaving her to die next to Hiroki.
When Yukiko shot with a dozen bullets, yet crawls to her friend Yumiko and holds her, crying softly.
The side chapter in the manga about Yuko's parents and their memories of their daughter.
In the manga, Fumiyo is seen in the flashback smelling flowers, talking to her friends, and crying during gym class, which makes her death much more jarring.
The chapter with Yoshimi and Yoji's death. Just imagine: you've left your past life of prostitution behind and have a loving boyfriend who makes you feel good about yourself... And then he turns on you and tries to kill you. Yoshimi tells Yoji that he can kill her if he wants, since she was truly happy being with him... Then Mitsuko pops up and kills Yoji right as he finally begins to understand. Of course, considering the circumstances, it might come across as more jarring than anything else.
The sequence at the beginning, where Shuuya and Yoshi see the broadcast of the end of a Battle Royale, with the girl who won smiling at the cameras insanely before their caregiver turns the TV off...and their questions later about what they saw:
"Will Shuuya and I have to go into the Program too?"
Their reaction just before.
Kid: "She looks like a monster Shuuya, why does she look like a—"
Right before Kiriyama's death in the manga only not just the revelation of his tragic past but when Shuya asks him how many fingers are on the trigger of the gun he his holding. It cuts back showing every student who fell in the Program and why they fell. This recap was more heartbreaking than anything else as we see not only most of the deaths but the reason for each death. It really shows that the majority of people in the Program were good, normal people who just gave into fear or died trying to do what was right whilst it is repeatedly mentioned throughout that scene drove it in. Many people criticise this by arguing that Shuya did not choose to play but the big difference was that he had Noriko besides him who acted as an anchor for his sanity and Kawada as a protector who had an escape plan. The only person who chose to play on his own free will was Kiriyama and that was because he had brain damage. Many people who played were simply alone and without any companionship they either gave into their fear or their sanity rapidly erroded.
In the manga, Shuuya dreams after having lost consciousness during his and Sugimura's dive of faith. Finding himself as his childhood version on some beach, he witnesses his mother, Yoshitoki and the recently deceased Shinji as all of them cite that Shuuya's time has not yet come and that there's still important things he's got left to do, such as protecting Noriko. Shinji returns several more times in Shuuya's thoughts during precarious situations, encouraging his friend to keep on fighting. Cue the waterworks.
Also in the manga, Shuuya eventually stumbles upon the exploded shack where Shinji died. Not only is Shinji's both tranquil and sorrowful expression in death heart-wrenching to watch, Shuuya makes it worse by hugging his corpse in the pouring rain, all the while having flashbacks of his fallen friend, lamenting his failure to protect him.
At the end of the manga, as Shuuya and Noriko are escaping Japan, they're huddled together down in the hold...and in one big splash page, we see all of their classmates, as well as Shinji's uncle and Hiroki's martial arts teacher, standing around them in spirit, smiling. "Never cheapen their deaths by pushing the memory away...Even the worst of them deserved better!"
In the manga, Yuko's parents looking at photos of their daughter, especially the one that has her standing with all her friends, looking actually happy. Knowing what happens to them...
In the manga, Noriko's futile last phone call to her mother... "All that trouble, so she could get a faceful of shit."
It gets worse when we find out why her mother demanded she turn herself in: The government took her younger brother and was effectively holding him hostage.
Mizuho's moment of relative lucidity, in which she mourns her dead friends, pleading with her "Elder Gods" about why Kaori and Megumi had to die ("I loved them.") Then, when her god-hallucinations ask her if she would elevate her 'unworthy' companions, Mizuho coldly dismisses their memory with a "No...they served their purpose."
Shuuya and Nobu's Say My Name moment in the movie before Nobu's necklace explodes.
In the manga, Megumi Eto's first scene has her hiding under a table, crying and wanting to go home. The memory of her family and Kamon's Yanking The Dog's Chain moment when he let her phone in her bag to make her believe that she could call home, onlyt to have him on the line. Then, she's killed by Mitsuko.
In the extended ending of the film, after all the teens have finished killing each other, there's a slow-mo flashback of a high school basketball game set to sad music. You see hints of how Ax-Crazy psycho bitch was really just lonely (though in the book her back story is a lot more horrific than mere ostracization) and you see how all the students used to be happy and normal and all that...
Ax-Crazy Mitsuko's death was also surprisingly sad. No last words or close-ups. Her dead body falls over and the voiceover says, "I just didn't want to be a loser anymore..."
The movie does flashback to a bit of modified backstory - before her death? - which is a lot more implicit than what she reveals in the book.
And Shogo's; the fact that its tearjerkiness makes sense doesn't really detract.
Also, the Reunion scene with Shuya and Noriko, supported by one of the most haunting themes in the film. Soaked, wounded and exhausted, Shuya can't even stay on his feet - but he is still devoted to his promise to protect his best friend's crush.