Test Island is an exclusive map only accessible by using cheese method and is meant to be for beta test only
Test Island preview
Overview
This island can only be accessed by teleporting with its ID and set coordinates to a small island for test purposes.
The island consist of Goddess Ilias, Seraph Eden, two adult Promesteins, Tamamo, Granberia, Erubetie, Kitsune and Alice unsealed version.
Features
Talking to Goddess Ilias will result in a new game plus like similar to Reaper's NG+ option after beating the game.
Difference will be that your companions, key items, will be kept instead of a do over, this loop hole can technically make the player play with Goddess Ilias and Alice at the same party, but there will be some bugs that may cause some events to not activate, or jumbled up making the other events never happened.
Example of using Test Island route.
Alice and Ilias