For an anime adaption. Couldn’t they just do the “Saya” approach that J.C. Staff did ? In Saya’s route in Little Busters!, (Saya’s route spoiler) I think it was episode 3’s ending, where Saya and Riki got to the end, then Saya went on to battle the Exucutives of Darkness’s boss aka Kyousuke. Then after that, she died, and we saw a title screen of a game, with the words “Game Over” and with the choices of “Quit” and “Replay” then she chose replay, narrating that she’s probably died more than 100 times. Then when she replayed, everything was reset (obviously), and we saw a new direction for her route. A direction that we’ve already seen, but a direction where thing things have been resetted.
Other than that, you can just add in some anime-original to the end of each route showing Kagari doing something. Obviously everyone will know what Kagari’s end scene during the end of each route foreshadowed.
I’d say
7-10 episodes for the Common route (since everything gets darker after that) so you might as well enjoy the 7-10 episodes of the days where everything was all fun and lollipop.
Kotori Route - 5 episodes
Lucia Route - 5 episodes
Chihaya Route - 5 episodes
That’s season 1, which is about 22-25 episodes.
Season 2 would start off with either Shizuru or Akane.
Shizuru would have 6 episodes
Akane would have 7 episodes
Moon would have 5 episodes
Terra would have 7 episodes
That’s around 25 episodes for a second season.
It would make sense that Rewrite would need a third season for a proper anime adaption, considering Little Busters! was shorter than CLANNAD, and CLANNAD is shorter than Rewrite. LB got 3 courses (EX not included). CLANNAD got 4 courses. So it would make sense if Rewrite got a third season (and yes, I understand anime adaptions aren’t perfect). Oh well. Most anime adaptions never get a third season, even if they are popular or not.
Then for OVA’s, I guess for the second season, they could do the Harvest Festa Route for Kagari.
For the first season, they could either do 1 OVA each for the Harvest Festa routes, 1 per girl, or they can just do OVA’s about the common route, since that’s what animation companies normally do.