Clannad After Story's Ending, Explained
Nagisa dies, Ushio dies, and time is turned back. What the orbs of light were, who the girl and the robot are, and whether the reset is a cheat.
Spoilers throughout. This page assumes you have finished the series.
Clannad ends by undoing its own worst hour. Nagisa dies, then Ushio dies, and then time is turned back to Ushio's birth and Nagisa lives, and the end of After Story is the series arguing that this is not a cheat. Whether it succeeds is the question every discussion of the ending comes down to, so it is worth being exact about what happens and what the show had set up.
The two seasons
The first season, twenty-four episodes, twenty-three of them broadcast from October 2007 to March 2008 and the last released on DVD in July 2008 by Kyoto Animation under director Tatsuya Ishihara, is a school comedy in which Tomoya Okazaki, a delinquent, helps Nagisa Furukawa revive the drama club and works his way through the other heroines' stories on the way. After Story, twenty-five episodes, twenty-four of them broadcast from October 2008 to March 2009 and the last released on DVD in July 2009, follows the two of them out of school and into a marriage, a job, a pregnancy and a death. Almost nothing in the first season announces what the second will do, except one thing.
The girl, the robot, and the orbs of light
The series cuts away to an empty world where a girl lives alone and builds herself a companion out of junk, and both seasons return to it without explanation. The other recurring detail is easier to miss: when Kotomi, whom Tomoya has helped, makes peace with her parents' deaths, her room fills with orbs of light, and in After Story he watches one rise into the sky. Yukine tells him and his friends the city's legend of the orbs of light, and the drama club's play, whose story neither Nagisa's parents nor Yukine recognize, is the girl and the robot's story told on a school stage. The frame narrative has been a school play all along, and the play has been the ending.
What happens
Nagisa goes into labor on a day of heavy snow, gives birth at home, and dies. Tomoya, who spent the first season becoming a person by taking care of people, abandons the one he has left: Ushio is raised by Nagisa's parents, Akio and Sanae, for five years while he drinks. A trip with his daughter is where the reconciliation happens, and it is where the series does something few anime have the nerve to do, which is give him back his own father as well, through his grandmother Shino, who tells him how hard his father worked to support him after his mother died. Then Ushio falls ill with her mother's sickness and dies in his arms in the snow, and Tomoya collapses.
The reset
The scene shifts to the empty world, where the girl and the robot reach the end of their journey together, and the girl calls the robot Daddy. That is the reveal: the girl is Ushio and the robot is Tomoya. Tomoya wakes at Ushio's birth, five years earlier, and this time Nagisa survives. The changed outcome is credited to the efforts of the girl in the illusionary world, and after the birth Tomoya and Nagisa see countless orbs of light floating through the city.
Is it a cheat?
The case that it is: the series stages two deaths and then removes them, and a viewer who wept at Nagisa's death is entitled to feel that the tears were extracted under false pretenses. The case that it is not, which is this site's, has three parts. First, the mechanism was planted in the first season rather than invented for the finale; the empty world and the lights predate the tragedy by more than a season. Second, the reset does not erase what Tomoya learned, because the version of him who wakes up is the one who has already lost everything and understood why he had a father. Third, and this is the argument Nagisa herself made at the foot of the hill in the first episode, the question the series asks is not whether things change but whether a place can be loved once they do, and the ending is the town answering yes. Compare Steins;Gate, whose rewind is earned by procedure, or Madoka Magica, whose rewrite costs its heroine her existence. Clannad's costs Tomoya five years he then gets to keep. It is the gentlest of the three, and the one most often accused of sentiment for exactly that reason.
Akio's speech about what parents do, and the lines on Tomoya's and Nagisa's pages, are all from the first season, because that is what is verifiable to this site's standard; the After Story dialogue is not yet sourced. The lines are on the Clannad quotes page.