Ep 13.5 or Another Epilogue episode:
In the BD/DVD-exclusive short "Another Epilogue", Otonashi remains in the school and becomes the new student council president, helping out other students to pass on.
The scene begins in a class showing students(NPC) starting on a test.
The scene then focuses on a boy with blond hair and red eyes. He stands and makes a fuss about knowing that he died without achieving anything. He then talks about the point of taking the test, whether does taking the test and achieving a good grade mean he will enter Heaven. Then he directs the question to the class, but of course them being mostly NPCs, no one answers.
Then the front door to the class opens and in walks the Student Council President, who is none other than Otonashi himself. He walks up to the blond hair boy, grabs his collar and sternly questions him. Otonashi is shown telling the boy to quit whinning and do something about the problem. He asks the boy if he has something he wants done and what Otonashi can do to help the boy get what he wants.
Then Otonashi refers to 3 of the SSS—Shinda Sekai Sensen (死んだ世界戦線?, lit. Afterlife War Front)'s members.
1. Iwasawa (岩沢?):
Otanashi says the line, "One needed courage to face the past." The next scene shows the cafeteria where Girls Dead Monster played. This refers to Iwasawa since she used music as an escape from her constantly fighting parents in life, but ended up dying from a brain injury she received. 
Otonashi then says the line, "Another person needed effort to make a dream come true." The following scene shows the baseball field. This could be a reference to either Yui and/or Hinata since Yui had regrets that ended up being finally fulfilled in the baseball field As for Hinata, he was a former baseball player missed a fly ball in a similar baseball game in life  The reference seems to point to Yui more so that Hinata, since she was the one who needed to make the most effort to have her dreams come true.
3. Yuri Nakamura (仲村 ゆり Nakamura Yuri?):
Otanashi lastly says the line, "Yet another person needed time and friends." The following scene shows the principal's office and the former base of the Afterlife War Front. Yuri vowed to fight against God after her three younger siblings were murdered by burglars when she was alive, and never forgave herself for failing to prevent their deaths. , after destroying all the computer and denying herself of being "God" of the temporary place, she was shown in a scene where her siblings thanked her for what she did. It seems through all the episodes, Yuri experiences a lot of things with the Afterlife Warfront and at the end cares for the Warfront just like she cared for her siblings. This answers the Time and Friends portion of what Otonashi referred to.
Otonashi is shown questioning the boy once again with the words "What about you?". The boy argues back saying that, right now, he needs the courage to stand up against Otonashi.
Otonashi is stunned for a moment and then smiles telling the boy that he can do it if the chooses to, and that he should know the way (to move on and disappear) now. Otonashi parts with the words "If you feel more anger at the unfairness of it all or lose your way, come to the Student Coucil room. I'll be there waiting," which simply means that, if you need anymore help, come and find me.
The scene ends with the NPC's chattering about Otonashi, who sits in the student council room with a vase of the flowers Kanade liked to grow. The teacher asks the class to quiet down, and the boy is shown one final time crushing the test paper in his hands as the teacher tells him to sit down. The Alternate ending finishes with the words "Next Stage".The End of the Alternate ending