Warning: Spoilers ahead.
Takt and Destiny face off against the new Musicart, Orpheus. She’s Heaven and Hell combined. As you’d expect, that makes her quite powerful.
She summons two massive harps that act as multi-ballistic-type weapons. Machine guns, missile barrages, proximity mines, you name it. To make matters even more difficult, Orpheus is able to regenerate her body quickly after taking damage. So if those ballistics hit her as well, that’s okay. She can heal.
Takt and Destiny realize they have two options - keep hitting Orpheus non-stop so she doesn’t have time to heal. Or hit her with a massive blast - a one-shot, with the same result as the first option. Destiny hits her with some shots as a first decoy. Then Takt follows up with a kick as decoy #2. She blocks that, but the attack gives Destiny enough time for the real blow. One of her mega blasts point blank. It melts Orpheus’ upper half to nothing.
But it’s not time to celebrate. She starts regenerating. Destiny promises to handle her once and for all while Talk confronts Sagan.
When Takt leaves, Orpheus recovers. She and Destiny engage in a thrilling sword fight. Orpheus is much stronger with her sword than Destiny. It devolves into a fist fight. And that’s when Destiny finally fucks up the bitch. Of course, this is all at great cost to Takt’s life force.
Sagan has a flashback of the war. Heaven and Hell were the Musicarts that stayed by his side to help win the war.
The tables were turned and the war was won, only through great sacrifice from the army. And somehow that leads him to go crazy, where he enjoys seeing people in pain. Makes no sense.
Takt finds Sagan completely impaled by Siderite but still alive. Sagan reveals that his plan was to call forth the remaining D2s to come out to this continent. Then…. seal the D2s in the continent? Somehow. And that would save the rest of the world. Sagan thinks sacrificing oneself is beautiful. Anyways, Takt shuts him up with his own nonsense - the power of music saves the world! Destiny arrives, and Takt uses her sword to stab him through. Neat!
With his death, the Siderite falls apart and the D2s die.
On the shore, Destiny and Takt lie down, exhausted. They seem to be holding hands, but Takt’s hand is the one that doesn’t exist. Takt hums his song. It’s the one he composed for Destiny to hear.
Takt starts to take a nap. Destiny gently kisses him. And then disappears, leaving a pendant.
Months pass. Anna becomes a Symphonica officer. She tells Lotte and Titan that she’s going to work while waiting for Takt to wake up from his cryo-sleep/treatment.
Then we see that Anna can call forth Destiny/Cosette to combine with her body, thanks to the pendant.