Yeah.. I'm sure I'm not even close to understanding this show 100%.

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Takakura's backstory

-Kanba was part of Masako's family. He followed his biological father into the terrorist organisation so his other siblings could live their rich life. Upon the death of his father, Kanba was accepted into the Takakura family.
-Shouma is the only blood-born of the Takakuras. He invited Himari into their family.
-Himari lived near the Takakura's meeting place. Her parents never took care of her. The Takakuras ended up taking her in.

Momoka & Co.'s backstory

-Momoka's been helping people with her spells.
-Yuri and the teacher were both saved by her.
-Momoka ran into Sanetoshi and was turned into 2 hats


Anime events
-Himari was dead from illness, but Momoka revived her and asked the Takakuras to obtain the Penguindrum.
-The Takakuras ran into various people trying to do so.
-Everybody believed the Penguindrum was Momoka's diary.
-Ringo wanted the diary to become Momoka
-Yuri wanted the diary to revive Momoka
-Masako wanted the diary to revive her brother.

Towards the end:
-Yuri no longer needed the diary because she found a new purpose.. and that reviving Momoka would be pointless
-Tabuki gave up on revenge against the Takakuras after finding the corpses
-Masako became more fixated with saving Kanba than saving her brother, ultimately got hurt and had the diary stolen/burnt.
-Kanba decided that helping Satenoshi was the only way to save Himari and prepared another terrorist attack
-Shouma wants to save Kanba and meets him on the train
-Ringo uses the diary to change fate instead of trying to be Momoka

What happened this episode:
-Ringo activated the spell
-Kanba died to transfer Himari to her new fate
-Shouma took the punishment for Ringo
-Kanba and Shouma were wiped from existence and everybody's memory. They are seemingly reincarnated
-Momoka is revived and leaves.

The confusing part:

-Why did Kanba have to die if Ringo was using the spell?
-What's with the two boxes locking Kanba and Shouma.. and the "penguindrum apple"? There has been no prior mention that these two were stuck in some life-threatening situation before.
-The apple can help them survive a little longer, but how did they get out?
-If Shouma returns his half of the Penguindrum to Kanba, how come Kanba still died? What's the point of that?
- What was that strange part in the aquarium where Himari goes into some hidden archive and meets Sanetoshi?