45,600 seats; the way home plate faces is not known (no diamond is mapped in the dome), so the field lies the way that fits the building and no arrow points north.
The picture above was drawn when the docs were built. The script below draws it again with the published package.
import { drawKyogijo } from "@johnmorrisdotca/kyogijo-stadiums";
const svg = drawKyogijo({ sport: "mlb", park: "tokyo-dome", crowd: { real: true } });
This page imports the package from jsDelivr (major version 0), which serves only versions that have been published to npm. A feature added after the last release is not in it: the page then keeps the picture above and says why. The docs were built from version 0.64.0.