Godzilla Against Mechagodzilla

-"I'm like Kiryu. My life is worthless."
-"What? No life is worthless!"
-"It isn't?"

—conversation between Akane Yashiro and Sara Yuhara

Godzilla Against Mechagodzilla, or Godzilla X Mechagodzilla, is the 26th film in the Godzilla franchise. It features the return of Mechagodzilla, and is unique among the Millenium series in that it actually references other films in the Toho canon. It is also one of only two films in the Millenium series to be directly related to each other.

Tropes used in Godzilla Against Mechagodzilla include:

Action Girl: Akane Yashiro.
A.I. Is a Crapshoot: As mentioned below, Kiryu goes completely apeshit upon hearing a real Godzilla's voice for the first time.
Battle in the Rain: At the beginning of the movie.
Big Damn Heroes: Kiryu bodyslams into Godzilla just as he's about to destroy a hospital that's being evacuated.
Haunted Technology: Kiryu. After hearing Godzilla's roar for the first time, he remembers his past life, and then turns into Yui Ikari.
Macross Missile Massacre: Kiryu is still a Mechagodzilla, so this is to be expected.
Missing Mom: Not really missing. When Sara's mom was pregenant with Sara's younger sibling, she became sick. Both her mom and sibling ended up dying, and Sara became very sensitive about life and death as a result.
Nigh Invulnerable: Godzilla shrugs off pretty much everything that's thrown at him, until Kiryu fires a maser from his mouth.
Intercontinuity Crossover: Both Mothra (1961) and War of the Gargantuas (1966) are mentioned and explicitly referenced in the film.
- It goes way beyond that. According to a Toho published guidebook, Varan (1957), The Mysterians (1958), Gorath (1960), Dogora (1964), Frankenstein vs. Baragon (1965) and King Kong Escapes (1967) are all in continuity with this movie and it's sequel.
Parental Abandonment: Part of why Akane believes herself to be worthless.
The Atoner: Akane.
What Measure Is a Non-Human?: Sara vouches for Kiryu. Even though Kiryu is a monster, he is still a living being. In many ways, this harkens back to Katsura from TOMG, as both characters are cyborgs.