The death of one of your monsters in Monster Rancher can be pretty upsetting, especially if you happen to be a little kid. All the effort you've put into raising your monster makes it even more personal.
Monster Rancher 2's is the worst—when you see shooting stars, you know your monster's going to go. In your barn, they keel over, and their pale, translucent ghost ascends to monster heaven. The sad music doesn't help. If you hold a funeral for your monster, Colt ends the affair by saying, "Let's come visit sometime..." You can avoid it by mixing monsters into new creations the moment they start showing signs of old age, but to unlock the Ghost, Mock and Wracky, you have to let at least one monster die.
Monster Rancher 3 is both better and worse in this area—better because when your monster dies, you get their "Monster Heart", full of their spirit (and stats) which you can give to your new monster to help them live on, worse because you have to watch the death scene every time to get it.
Phoenixes fly off into the horizon when the end of their life approaches, and it's pretty obvious that they're struggling to do so. Colt will not react well to a Phoenix's departure, especially because she knows that they're flying off to die alone.
What the Stimulants do to the monsters in Monster Rancher 2—specifically, up your monster's stats, but dramatically reduce their lifespan. If you don't know the downsides, you can drive monsters to their ludicrously premature grave for the sake of the fight.
The death feature made some people stop playing the game. Especially since it can happen just as you're really getting into the training and showing serious results.
You can get a generic Merchant Zuum just to work it to death, and it still won't be any easier to watch it die. "Goodbye, A."
The Sueki Suezo is a man-made clone of Suezo. It dies in one week, and you can't give it Silver or Golden Peaches to increase its lifespan.
One of the themes of Monster Rancher 4 is trainers using horrible methods to increase their monsters' strength. One such method is modifying monsters with rusty, ancient materials. One of your rivals eventually does this to his Golem to try and catch up with your hero. At first, he claims that Dodongo was perfectly okay with this; Rio calls him out, spelling out how Dodongo only went along with the painful procedure to make him happy. She strips away all of Gramm's illusions and makes him break down with horror upon realizing what he's done to his best friend.
Another one of your rivals runs his ranch by forcing monsters to run on training gadgets all the time, in tiny little pens. When he shows off his ranch, he brags about its efficiency, and how his ranch is on the cutting edge.
In Monster Rancher 4, Phayne once had a Mocchi. He had no parents, so it was his only friend. But he treated it more like a stuffed animal, never thinking about its feelings or needs. One day, when his Mocchi didn't even want to be outside, they were attacked by a stray monster. The Mocchi lunged for it, and they both fell into the sea. After that, Phayne was unable to raise Mocchis. It has a happy ending, though. After you beat Geras, Phayne's Mocchi returns, and is said to be living comfortably with other Mocchis.
The death of Monsters in general was so sad that 4, EVO, and the Advance games took out the death feature. It returned in Monster Rancher DS, where the death of a monster is similar to Monster Rancher 2.
ThisLet's Play of Monster Rancher 2 has one with whatthef the Ducken's death right after winning the S Cup. It hits even harder when in the author's previousMonster Rancher 1 LP, he deliberately worked Bongo the Naga to death and celebrated when he finally died. In this, both Colt and the author are distraught.
The full versions of the first and third Japanese openings, as well as the English ending theme.
Episode 2 has one with Mocchi thinking Genki doesn't love him and running away in the rain. Mocchi thought that in the first place because Genki tried to give him to an elderly couple who longed for a monster to love and who Genki thought would take better care of Mocchi than he would.
Holly berates Genki for thinking the problems Moo caused are like a video game. She reminds him that in this world, Moo is not a game and the destruction he caused was very real. Given what we learn of Holly's past in episode 8, this sequence is even sadder.
The episode that introduced Golem, when it was revealed why he was in the lonely castle. He was guarding the Lost Disks of monsters that couldn't be revived.
Later, in an Unstoppable Rage, Golem destroys some Jell troops, including one that begged for mercy. When he finally snaps out of it and realizes what he's done, he starts crying... and a tear lands on a flower and makes it bloom.
The episode "Eternal Worm." For the most part, Allan came across as an Anti-Hero at best and a jerk at worst, abusing and insulting his Worm monster. It got so bad that when the Seed Sisters asked Worm if it wanted to join the baddies, it accepted. However, it cut Genki and the others free instead, still loyal to its master. Enraged at being tricked, the sisters sucked the life out of the Worm and made it a Lost Disk... and Allan realized just how much he'd done with the Worm and how he loved it.
After defeating the baddies, Allan places flowers on the Worm's grave, remembering the good times he'd shared with it, complete with a Really Dead Montage. Then, Genki and the others walk up and show him the monster they'd just unlocked. It was a baby Worm, and they said he could keep it—as long as he treated it right.
Tiger: You're a very brave, and very foolish little human. You rush in head first not bothering to even think of the consequences. You don't understand that sometimes, bravery isn't enough. Life can be hard, little human, hard and unfair—and you must know this. Don't. Be. Reckless. You're young, brave, and you have a good heart—but in this world, that isn't enough. I know that better than anyone.
The slaying of Tiger's pack in his introductory episode. Brian Drummond's voice acting nails it.
Everything involving Holly and her father, especially when she learns he's Moo's vessel.
"Amusement Park Ruins" has everyone's delight at the old amusement park, especially when Pixie's lightning gets it working again. What makes it sad is when it stops working, all the lights go out, and everyone is saddened.
Undine's Redemption Equals Death. Golem tries to save her, but she jumps into the fire herself. In the end he tosses flowers into her lake in memory, and Holly says that she wasn't really evil in her heart.
Tiger's reunion with his brother Gray Wolf, only for them to have a battle to the death. At one point, as Gray Wolf was telling him to join him, Tiger refused, replying that he would lose something too important. And for the first time, we see Tiger shedding a single tear. And as Gray Wolf was dying:
Gray Wolf: I wish we could just go back to when we were pups...
One editing of the English dub replayed a flashback of the brothers' time as pups after that line. It ended with Gray Wolf telling Tiger he's the best brother ever, and that he loves him... and cut back to Gray Wolf dying immediately after.
As Gray Wolf gets the upper hand with a dirty trick and Tiger still refuses to join him, Gray Wolf snaps.
Gray Wolf: You don't have a clue how I really feel! I'm grateful to Lord Moo for saving me! I was only able to build up these new powers of mine because I met up with Master Moo, and that's how I rose up in the ranks.
Tiger: You're nothing but a lapdog.
Gray Wolf:Silence! I'm gonna give you one last chance now. Join our side. Become evil like us and you'll be bestowed with great new powers.
Tiger:*crying* No. I'd lose something too important.
Gray Wolf: You're blind! You'll never understand how I feel! You always looked down on me, always acting so smug! Ever since we were pups you thought you were better than me!
After Gray Wolf dies, his Lost Disk is quickly covered by snow. Tiger howls in grief.
A dub-induced one in "Battle With the Big Bad Four." In the uncut Japanese version, Suezo sees visions of his lost friends and gets the Heroic Resolve to attack Naga one last time, biting his arm so hard it's rendered immobile. In the dub, his attack was cut out, but not the scene leading up to it, making it seem as if he asked for strength...and failed.
Suezo: My buddies...My good friends... Please, help me. Lend me your strength.
Naga's suicide. Genki, Holly, and the others, even Suezo, try to save him from falling to his death after all he'd done to them. Naga looks up at them and lowers his head.
Naga: ...So that's why you're all so strong. *lets go of the ledge*
"Holly's Happy Birthday" states that Holly turned 15, meaning everything bad that happened to her before then was when she was 14 and younger.
"Goodbye, Baku". Even if you're not a dog lover, you will be bawling by the end. Basically, Genki and company found a Baku, a monster who's like a big friendly dog. It latched onto Genki immediately, protecting him from harm. As it turns out, the Baku's owner (and said owner's parents) had been killed by Moo's forces, and his owner looked like Genki. As a puppy, he tried to fight them off, but failed.
It gets sadder. The Chariot that destroyed the village Baku lived in came back to attack the heroes. Baku defeated him, but was mortally wounded in the fight. So he went back to the house and curled up in front of a picture of his owner before dying. The last image we see in that episode is a flashback of him and his owner happily playing.
"Tiger Meets His Match" is a pretty big tearjerker thanks to Jagged Hound's Backstory and the others being led to think Tiger was killed. We even get a Really Dead Montage before it's revealed Tiger was faking it.
Captain Astro. He tells Genki and Holly of how the ancient people ran out of resources and forced the Astros to look for more, working them well past their breaking points. Many of the Astros died, and now the Captain accuses humans of being evil and destructive. Genki tells him that not all humans are like that, but he won't listen...until Genki risks everything to save his life as they're about to go down a waterfall. With Suezo's grip on them weakening, Astro shoots his rocket fist to save Genki, finally realizing not all humans are bad. Despite the fall, Captain Astro meets with his troops and tells them to call off their war on the humans, asking that they try to enjoy their freedom...and then dies.
Genki was absolutely heartbroken over it, only jumping up happily after being prompted to. But as he was crying, one of the other Astros wiped away his tears.
The aptly named "Tears", which leads directly into the second season finale. It features Pixie, Big Blue, and the Dragon Army returning...but Pixie is mortally wounded fighting Moo. Big Blue decides to fuse with her to save her, even though it means he'd utterly cease to exist. He goes through with it, saying it's worth it if she lives. Pixie is reborn as Granity...and then she wonders where Big Blue is and why everyone's crying.
The season two Downer Ending was a killer, especially for a children's series. In the space of a single episode all the Mons sacrificed themselves to resurrect the Phoenix, the Phoenix sacrificed itself to kill the Big Bad and the resulting explosion threw the main character off the back of the dragon he was sitting on... to collapse straight onto his back in the real world once again, rain falling onto grey streets. The sight of the Angst? What Angst? main character breaking down into tears over the trauma had many kids crying along with him.
Even then, you may hold it together until you see the spirits of the Monsters saying goodbye to Genki, before they fused. What really nails it is Mocchi's "I love you, Genki..."
The Monsters resolving to fuse in the first place and encouraging Genki despite his heartbreak over the situation.
Tiger: You said you were going to destroy Moo and make this world a peaceful place again. I came all this way because I believed in what you said.
Golem: Golem feels the same. Your determination gave Golem hope!
Hare: You know, you were the best motivation ever, Genki!
Genki: ...You guys...really?
Tiger: So even if it means that we disappear...
Suezo: HOLD ON! I WANNA BE THE ONE TO SAY IT! ...We'll have no regrets if we can become the Phoenix.
Mocchi: Mocchi, too!
After Genki's return to his world, he smiles and sees the shoes the old couple gave him when he first arrived there, reassuring himself that the Monster Rancher world was real... and then gets flooded with memories of his friends and the time he spent there. Genki breaks down into tears over it and punches the ground, and it's made even worse by the fact that aside from Holly all of his friends are dead at this point. Luckily, Genki soon sees a vision of his friends, who comfort him and say they'll always be with him in his heart.
Even the music used in sad situations, in both versions—the Japanese one has a simple, sad piano theme, while the American one has an orchestrated sad theme.
After watching the second season finale, the ending theme can cause one to tear up.
Genki's reunion with everyone in Season 3, especially Holly and Mocchi.
Episode 73 has Mum Mew screaming that she likes herself just as she is when Moo's soul starts to consume her and the others. After an entire season of buying exercise gadgets and hating being called old, when her life is on the line Mum Mew accepts herself and her body image.