The location of a Google App Engine application is a permanent setting chosen during its initial creation within a Google Cloud project. This location cannot be changed after the application is created. Furthermore, a single Google Cloud project can contain only one App Engine application. Therefore, to deploy the application in a new region (asia-northeast1), you must create an entirely new Google Cloud project. Within this new project, you can then create a new App Engine application and specify asia-northeast1 as its serving location during the setup process.

A. The project's default region setting primarily affects services like Compute Engine and does not alter the immutable location of an existing App Engine application.

B. The region of an App Engine application is an immutable property. It is set once at creation and cannot be modified later.

C. A Google Cloud project is limited to a single App Engine application. It is not possible to create a second one within the same project.

1. Google Cloud Documentation

App Engine Locations: "When you create an app

you must choose a location... The location you choose for your app is permanent and cannot be changed." This document also states

"Each Google Cloud project can contain only one App Engine app."

Source: Google Cloud

App Engine Locations

"Choosing a location" and "Location and your project" sections. https://cloud.google.com/appengine/docs/locations

2. Google Cloud SDK Documentation

gcloud app create: The official command-line tool documentation for creating an App Engine application explicitly states for the --region flag: "The region to create the App Engine application in. You can't change the region after you set it."

Source: Google Cloud SDK

gcloud app create

Command description. https://cloud.google.com/sdk/gcloud/reference/app/create