Secondly, Index explain that the Amakusa uses a special magic that involves 47 gateways/portals that are almost untrackable to evade and hide from their enemies. What the anime didn't explain in detail was how this spell came about. The name of this spell base on the [
Dai Nihon Enkai Yochi Zenzu] (大日本沿海輿地全図 maps of Japan's coastal area) that the famous Japanese surveyor
Ino Tadataka created by using
Idol Theory. The short explaination for Idol Theory goes like this; If you create a replica of a magic symbol, they would be able to harness the power of that magic symbol. For example, if one were to build a duplicate of the cross when Christ was crucified, and put it on the roof of a church, they’ll get some Holy power from those actual Cross wielders. Although the power of the duplicate is not even
0.000000000001% of the original.
However, the opposite also works the same, it is through the replica, one can also affect the original, but this is still a Hypothesis and isn't 100% confirmed. Ino Tadataka used this ‘Idol Theory’ in the opposite manner. He understood that the real one and the idol will affect each other, so he plotted 47 ‘portals’ on the Dai Nihon Enkai Yochi Zenzu that originally didn’t exist on the Japanese islands. Thus, these entrances that allow people to come and go as they please appeared in modern Japan. For those wondering if that map can be used as an IWIN button, the condition for being an idol is being a ‘
duplicate’; as long as there’s even a slight difference in the levels of magic used between the idol and the original, the idol will lose its purpose. So, the ‘Idol Theory’ can’t be used to solve everything. Once the original ‘image’ is changed, the theory cannot be used. Index explained that There was a group of magicians in the past who tried to use a stone sculpture that looked like the ‘
Son of God’ to control the ‘
Son of God’ in the heavens, but it ended up in failure.