 It's quite likely that the author intentionally made the ending open-ended, so that the audience can interpret whether Aiko is still alive or not.However, it's quite likely that Aiko is still alive as we see her alive and well at the end with her meeting with the person who called out to her, but there's no confirmation whether she is alive.Regardless, it's up to the audience to interpret whether Aiko is still alive as seen at the ens of the story when we see her walking in a city sometime after the public knows about Atheos and the Chimeras.