This was apparently a calculated move to keep Ieyasu far from Kyoto, where the emperor ​ — the figurehead of Japan — ​ lived.
Tõenäoliselt oli see Hideyoshi poolt kaalutletud samm, et hoida Ieyasu eemal Koyotost, kus sel ajal elas Jaapani keiser, kes oli valitseja vaid nime poolest.