Elemental War Arts and Extra Archetypes
The second piece of creation to migrate over for me are the Elemental War Arts that were the very first thing I ever made for Tenra along with some original Archetypes. I love war arts. They over so much flavor and are really easy to tinker with to make something original for a character.
The archetypes include 7 to go along with the 7 war arts but also have ideas for specific Ayakashi. Ayakashi are such a cool idea but I find it takes a bit of work to put together powers and weaknesses so I put together 6 archetypes based on specific creatures of legend. Only 2 of them are Japanese though as at the time I was not knowledgable enough to do more. I would properly do a lot more now that my mythology knowledge has leveled up.
The last few archetypes were just random fun bits I put together that are not in the book. Specifically, the Person from Another World is just something I wanted since I am a fan of the Japanese Isekai genre.