It's written in the last of Miko events, in bold letters like this just after the words "A word appears in your mind, it seems to be a password"
I can guarantee that it's in the game.
It didnt show up for me :'( and i can guarantee it
I'm sure that it works as I programmed it, tested it and others have found the password.
If you reach the event again you should be able to read it.
On the other hand, when I have more free time I can add the password to the last of Miko's images in the gallery but it shouldn't be necessary.
Alright ill try and see if that works