Slight delay here, I was too busy with Mantlecon yesterday. Comic also later today.
But without any further delays, Angel Beats! Episode 3 reveals a *tiny* bit  more about the world they’re in..

This episode starts with Iwasawa showing Yuri & co her new song for the next concert of GirlDeMo.
But apparently, Yuri thinks a mere Ballad would prevent them from doing anything showy.
But it’s good enough for a distraction.

Yuri then proceeds to give the briefing for their next operation: They will infiltrate Tenshi’s lair.
Apparently the SSS did so in the past and it failed horribly, so this time Yuri got a hacker coming with them, who wants to be called “Christ”.
Meanwhile, Otonashi has some familiar images of Tenshi’s lair in his head..

After the meeting is over, Otonashi did some training by shooting cans.
He’s surprised how good he has become, though maybe he’s enjoying it a little too much?
As Otonashi is walking through the hallways, he bumps into Yui (Miss Pink appears!!) who is putting GirlDeMo posters on the board.
Apparently Yui knows him because her senpai with the giant axe told her to be wary of this new guy, because he brings calamity or something with him.
Otonashi asks if its really ok to put all those posters there, advertising where the concert is.
Yui responds that it’s quite dangerous and unheard of! But the plan this time really needs a huge audience so it will grab Tenshi’s attention.
Yui then talks on about her love for GirlDeMo…

After that, Otonashi decides to check the music room, where GirlDeMo just got a small break after practicing.
Iwasawa and Otonashi talk a little till Iwasawa’s past comes up.
Her parents were always fighting and since she didn’t have a room of her own, she would just hide and endure it all.
One day she decided to listen to some music at a store through the headphones, since she heard it had a positive effect or some kind.
This was the moment that she realized she could escape to her own world.
She found a guitar on the street and started practicing and playing on it. Singing songs in the streets.
Even though with her grades she could go to a good school, she wanted to become a musician and move out of her parents house, not depending anymore.
But fate was too cruel.

After a fight with her parents, she collapsed at her part time job.
When she woke up, she was in the hospital and could not speak.
Cerebral contusion. Aphasia due a stroke, they said.
She couldn’t move, she had nowhere to escape.
And like that, her life ended.

After she’s done with her story, her band mates call her back for more practice.
Otonashi then realizes everyone has their reasons to rebel against God.

Then we see Tenshi ripping off the posters from earlier.
The NPC students are complaining that it’s their only joy in the school.
Tenshi ponders why this makes her look like the bad one.. ;_;

The appointed time has come and GirlDeMo start their concert!
Meanwhile, the SSS invade Tenshi’s Lair! ..
Otonashi flips on the light and it’s just like any other girls room in the Girls Dormitory.
He loses faith in the SSS for a bit.

Meanwhile, there aren’t enough people at the concert yet. Iwasawa decides to play Alchemy earlier than usual, which hopefully grabs more attention.. With success.
Tenshi has arrived at the concert.

They access Tenshi’s computer with their hacker comrade and find .. Student name register.
Having both the names of the NPCs and humans.
They’re running out of time though..

Tenshi leaves the hall and the teachers are ready to stop the concert
Confiscating the instruments.
As a PE teacher grabs Iwasawa’s guitar, she falls into a rage and pushes the teachers aside to save it.
Her band members stop the other teachers from interfering.
Then like on cue, she starts singing her ballad..

The ballad is broadcasted through speakers all over the school, which makes Tenshi return.
During this, the SSS discover something else on Tenshi’s PC.
The screen reads harmonics.

As Iwasawa ends her song, she feels like she has found what she was looking for.
The guitar falls on the floor and she is nowhere to be found..

The next day, the SSS discuss what they found on Tenshi’s PC.
Apparently, she does not get her powers from God, but makes them herself like the SSS get their weapons.
Yuri cannot understand why this is the case! Why does Tenshi have to dveelop her own powers? It can only mean one thing then..

Then the next issue comes up.. Where did Iwasawa disappear to?
Tenshi couldn’t have erased her. It was in the middle of a concert!
No one erased her. She accepted it herself. That’s all there is to it..

They say that you only disappear when you do what Tenshi does. But that is not the case.
There are other ways..

The ED comes up, with a change.
Iwasawa is not there anymore, and the geek hacker has been added.
Iwasawa, you will be missed ;_;

As for my speculation, Yui will probably join GirlDeMo now.
Kudryavka 2.0 on promo art with the other 3 mains means she won’t be a side character for long..