Season 1 - Yuu goes to the school and him and the main cast go through the searching for kids with powers arc. Slowly Yuu starts getting flashbacks about his past. Tension is building with the unstable girl who killed Ayumi around her mental state and we see her plan to kill Ayumi. The season ends with Ayumi's death.
Season 2 - The season starts with Yuu grieving over his sisters death. In the first 3 episodes or so we see him go down his dark path and then get saved from this path by Tomori. Yuu then goes back to finding kids with powers with the main cast again but his flashbacks are happening more often. Yuu tries to discover his strange past but he can only get bits and pieces. Here Yuu meets the lead singer of Tomori's favourite band and we get the sequence of events that transpires in the anime which leads to his realisation. This season ends with Yuu finding his brother.
Season 3 - Yuu's brother explains the truth about Yuu's past and explains everything as seen in the anime about the school and the source of the special abilities. Yuu now realizing he has the time jump ability asks for his brothers help to save Ayumi but his brother refuses saying time is not to be meddled with because of a early incident caused by his multiple time jumps while trying to escape the science institute. Yuu enlists the help of Tomori and they plan their mission together and time jump back and save Ayumi. Once they get back all is well but the scientist explains that the vaccine will not work and they cannot make a new one before the comet comes around in about a 3 years time. The season ends. It is also implied that Yuu's brother knows he time jumped.
Season 4 (25 ep) - At the start of the season Yuu realises he has the power to vaccinate people from the disease. He got this power from someone who he momentarily possessed in season 2. In season 4 Yuu goes off on his journey to rid the world of the powers as seen in the last episode of the actual anime. This season is the culmination of Yuu's character arc from a self centred, selfish teenager to a hero. On Yuu's journey across the world he meets an extremely powerful girl his age who has telekinetic powers. She is a lone ranger in the middle east who's whole family died during terrorist bombing. Yuu and her slowly take their journey over 3 years. Throughout this time tension builds as the comet comes closer and closer to Earth. At the end of the anime Yuu and the girl only just vaccinate the world with Yuu dying at the end as a result of using too many powers. Just before he dies he passes on an ability to the girl which allows her to bring back her family but makes her promise not to use it on anybody else ever. By dying to save the world Yuu completes his character arc.
END OF CHARLOTTE
