So, my idea was going to be having a character who learned the cp9 techniques (or an offshoot rather) from his father/mentor who used to be a member or know a member of Cipher Pol.
My question is this: If it makes sense how his mentor learned it and passed it on to him can i go ahead with this character idea? or are CP9 techniques and anything similar to them off limits?
Note: By CP9 techniques i mean: Soru, Shigan, Geppou, Rankyaku and Tekkai