It was Angel Beats.
At first, I didn’t really like the plot because of the part where Yurippe (the leader of the battlefront which they kept on revising the name) was questioning the presence of God but I thought, it would be interesting to know what she finds out in the end that’s why I kept on watching. It is a 13-episode anime with a lot of main characters.
I don’t want to spoil the ending because this is just a short series so I can just give you a brief introduction about it. Angel Beats is about a place where people who had an “unfair” life go after they die. The ones in here are mostly those who had their deaths early and didn’t have much time to enjoy their childhood some wander around due to memory-loss.
This anime revolves around fighting for what makes you happy and accepting the consequences once you reach it. And of course, love is also involved. The twists in the end made me cry most. And I still have a lot of questions.