Even the Americanized version of Godzilla includes a few. The whole reason Steve Martin was in Japan to begin with was because he was on his way to Cairo, and decided to stay a few days because he wanted to spend time with his college friend, Dr. Serizawa. This decision leads him to witness untold death and destruction. And the ending, as he watches his friend Dr. Serizawa sacrifice himself, he does so with a glazed, empty look in his eyes. It's impossible to tell if it's because of the head injury he received, or because he's in the beginning stages of PTSD.
Alien 2: *groaning and in form of a cockroach* I'm here...but what wrong?
Alien 1: And why!? Why did the machines go wrong? *morphs into true form and gives a painful dying groan* Everything was going so perfect...going so well! *death groan*
Terror of Mechagodzilla. Just...Terror of Mechagodzilla. From Titanosaurus, a normally very timid and placid creature, being forced to kill people and destroy cities against his will, Katsura's suicide, Mafune's death, Godzilla getting tag-teamed by two foes, both of which rival or exceed him in power, Titanosaurus' demise, the whole film is essentially a Tear Jerker.
Ichinose: You shed tears... Then you are human. You have a human heart like anyone else!
Godzilla plunging into Mt. Mihara at the end of "Godzilla 1985," followed by Raymond Burr's ending monologue:
"Nature has a way sometimes of reminding Man of just how small he is. She occasionally throws up terrible offspring's of our pride and carelessness to remind us of how puny we really are in the face of a tornado, an earthquake, or a Godzilla. The reckless ambitions of Man are often dwarfed by their dangerous consequences. For now, Godzilla - that strangely innocent and tragic monster - has gone to earth. Whether he returns or not, or is never again seen by human eyes, the things he has taught us remain..."
Godzilla's pitiful roar as the ground explodes beneath him and he suddenly begins plunging into the volcano is one of the sadder moments of the series. Martin's ending dialogue following after is really just icing on the cake, especially this line:
"For now, Godzilla - that strangely innocent and tragic monster - has gone to earth."
The Love theme which comes in the credits certainly makes the whole thing much more sadder, particularly with its beautiful, yet mournful lyrics.
The Manga adaptation of the film heartrendingly elaborates further:
"And so, at last, Godzilla was sent back into the belly of the earth. The news flashed around the world'Godzilla is dead, and many, no doubt, slept easier after that. But to those of us who stood on the slopes of Mt. Mihara that day and watched as Godzilla was slowly buried beneath the flood of molten rock, his cries did not sound like those of a dying beast. Rather, they conveyed a sense of sadnessa regret that his freedom should be so brief. For all the destruction he caused, Godzilla acted only according to his instincts. In that sense, he is beyond good and evil as we would define it. And I believe all those who were witness to Godzillas entombment realized this fact, and, to some extent, were also saddened. To this day, I can still hear the echo of those screams. But in them I now hear something elsea deeper note beyond the sadness I hear a threat. A threat that one day, as civilization revels in its own advanceseven as it destroys the balance of the worldGodzilla may again rise up from the depths and challenge mankind for possession of the world. And my deepest fear is that man, in his arrogance, will not heed the reality of that threatthat Godzilla will not rest in peace."
One scene in Godzilla vs. King Ghidorah (1991): A Japanese WWII veteran turned mega business mogul comes face to face with Godzilla, who had saved his troops from an American Attack during WWII before he was even Godzilla. As the sad music starts to swell, you can see the recognition in Godzilla's eyes amid the flashbacks to said time in the past. It looked as if Godzilla was cherishing said memories. And then, after the businessman nods, as if saying "yes, it's me", Godzilla roars (mournfully?) and promptly blasts the man into oblivion with his breath weapon. Alternatively, this scene can be interpreted in two ways:
Godzilla being tormented by those memories rather than cherishing them. Note how the flashback isn't about how Godzilla fought off the American soldiers, but rather about how the Japanese soldiers left him to die. He remembered the veteran alright, but not as an old friend, as the human who abandoned him. Maybe that was the moment that cemented Godzilla's hatred of humans.
Godzilla is, well, still pretty damn pissed off. He destroys stuff and buildings with loads of people still inside, who either die by radiation poisoning, burned to death or crushed by rubble or suffocate under the debris. He's also angry at humanity for making him into a mutated monster via a nuclear sub. But he sees the general and becomes sentimental because somewhere, under all that anger, there's the heart of a sad and suffering animal. He knows the man meant him no harm as he remembers how they respected him after his Heroic Sacrifice. He then becomes confused, as he hates humanity but likes this guy. Until Shindo gave a Godzilla a small nod, as if to say "it's okay, go ahead." So, in the end, he decides to give the general a quick and relatively painless death rather than the potential suffering he gave to millions of others.
Word of God explains it this way: Shindo was responsible for Godzilla's creation (or so he thought, not knowing that Godzilla already existed and his submarine had nothing to do with it). HE had turned his savior into this destructive monster— the bane of his homeland, and so he asks Godzilla to kill him (the nod at the end of the scene) because he could not bear to live with this. Godzilla complies.
Godzilla Junior was just a cute, lovable baby during the events of Godzilla vs. Mechagodzilla II, being raised by a kindly biologist named Azusa Gozo. It's established that he imprinted on her while in his egg and saw her as his mother. At the end, Azusa tearfully knows she can't care for him anymore and tries to get him to go with Godzilla. When she attempts to board the escape chopper, Junior tugged on her coat like a scared puppy and didn't want her to leave. After she embraces the infant and tells him they have to part ways, you can see Junior weeping. It's possibly the first time in the franchise we've ever seen a kaiju visibly cry.
And the music does NOT help one bit.
What also doesn't help is how heartbroken Asuza really is. Even in the English dub, the voice actress for her sounds like she's giving her waterworks overtime. That was the last time either of them saw each other as Asuza didn't show up in later movie. Although it would lead to further heartbreak to see her child die in front of her.
Plus, after Gojo leaves and Godzilla shows up, Baby's first reaction is to run in fear back to his holding crate.
Godzilla's own demise (and subsequent revival as Rodan sacrifices himself) at the hands of Mechagodzilla also counts; especially considering how Godzilla was really only looking for Baby, and would have left on peaceful terms had humanity not irrationally unleashed Mechagodzilla on him with little hesitation. Remember that this Godzilla is (supposedly) psychic.
The end of Godzilla vs. Destoroyah: Godzilla dies a slow and painful death due to a nuclear meltdown. That and when Godzilla mourns the death of his own son and cries in agony. It's perhaps the saddest Godzilla movie ever made. The music, really doesn't help either.
Then tears of joy when Godzilla Junior is revived.
Rebirth of Mothra Trilogy
Rebirth of Mothra trilogy: The death of Mothra Leo's mother is very tear-inducing. What can especially get you is Mothra Leo putting his head under her wing, crooning for her not to leave him and trying to prevent her from drowning. He fails and she sinks into the ocean with very sad music. Every a reviewer who picked on the film at Million Monkey's Theator said it was an emotionally draining scene for two models made out of rubber and styrofoam.
"Goodbye, Yoshido." (This is what Kiryu (aka the 3rd MechaGodzilla) says to one of the main characters right before sacrificing himself to save Godzilla from death at the end of Godzilla Tokyo SOS.)
"We knew the world would not be the same. A few people...laughed...a few people cried. Most people were silent. I remembered the line from the Hindu scripture, the Bhagavad-Gita. Vishnu...is trying to persuade the prince that...he should do his duty. And...to impress him...takes on his multi-armed form...and says, 'Now I am become Death, the destroyer of worlds.'"
Shin Godzilla has Shin Godzilla's Villain Song "Who Will Know (Tragedy)", mournful theme from Godzilla's perspective where the beast is torn between succumbing to his hopelessness and a drive to push forward and survive if only for a little while longer.
In issue 2 of Godzilla: Kingdom of Monsters, there is a father who has lost his children to Godzilla in issue one. He spends the first half of the issue questioning why this monster would take away his children. It ends with him strapping explosives to his body and throwing himself at Godzilla, detonating them and only giving the King of the Monsters a nose itch.
You took my children from me!
From the sequel to Godzilla Kingdom of Monsters we had the death of Urv. Also, in the first issue, Boxer's flashbacks after his charge is killed by a bunch of rednecks trying to take down Godzilla which focus on his daughter who was killed by Godzilla's first rampage on American soil.
Also from the comic, Harrison, Boxer's sondoesn't speak as he took a code of silence the day Boxer left him and his mother when he was only nine-years-old and would only speak again when he came back. He still doesn't talk, even when Boxer tries to make amends.
Boxer: Look, kid. I really hate letting you out of my sight. But this is the only way the plan can work. I mean, you realize why I brought you along... To keep you safe, right? Curse at me if you want. Just give me something. A word. A syllable. Tell me you understand!
When Hikari is knocked out due to Kiryu being flooded, Boxer tries desperately to revive her.
I can't lose another child.
The death of Boxer.
From Godzilla: The Half-Century War, we are given the death of Colonel Schooler and Ota's reaction. Manly Tears, people. Manly tears.
How about Ota's heroic sacrifice in the final issue? Even the manly tears shed manly tears that day. Especially when he's yelling at Godzilla to look at him and fight just before the Dimension Tide's black hole collapses on itself. And the kicker? Godzilla is still alive.
Godzilla: Rulers of Earth has a couple of these:
Sanda reaching out for Gaira as the latter is fighting Varan. This hits especially hard in a later issue when he finds out his brother hates humanity because of how they locked him up.
Dr. Allison is more than thrilled to see a Devonian. However, in issue 12, it turns out the one good Devonian was really the Cryog emperor in disguise. To make it worse, the Emperor kills him.
Godzilla's seeming death via nuke.
The death of Mothra and the destruction of Infant Island.