Here are some resources you can use to plan or make your lesson plans with your JTE or get some ideas for the English books your school uses.
SCHOOL: ES | JHS | HS | Special Needs
Free website with Japanese related cartoons for any scenario. Website is in Japanese but does have a search in English box.
This a resource sharing facebook group with active teachers in Japan. You can use it to ask questions or share class ideas and files.
BOOKS: Sunshine 1, 2 & 3 | Hi, friends! 1 & 2