A 200 piece orchestra, I can understand.
A 400 person chorus is like 'holy shit!'
Damn, they're bringing out da big guns!
Since this is Hisaishi, tickets do sell out quickly.
But according to wikipedia, Nippon Budokan is an arena with 14,000 seats. Even so, tickets might or might not sell out.
Another one of his works I heard recently was "The Legend (of the 4 Gods)", Terrible Korean TV series but great score
I think there's some influence from Princess Mononoke here, so look for some samples. The words "epic" and "dramatic" could describe this score.
I'm excited to see this new Ghibli film, Ponyo.
Haven't listened to the score yet though.