The intro to episode 12; the world is close to being destroyed, and it reflects that.
Jennifer: Well, we've taken a lot of byroads, but this long, yet short, ugly, yet beautiful story is coming to an end. Thanks for watching it all the way through. Bye, now~
Tear Jerker: There are moments where the series comes darn close by any criteria. For example: Takeru's childhood abandonment, the sheer desperation of Akira and Hikari in the final episodes, and the quasi Downer Ending.
The Woobie: Both Hikari & Akari when they are tortured by the reality of their true mission on Earth (to decide whether or not to destroy the planet).