any good yaoi mangas about ninjas?

Not that I know of, but there is this:

http://www.mangago.zone/read-manga/gakuran_ninpouchou/

http://www.mangago.zone/read-manga/kyoukasho_no_koibito/
http://www.mangago.zone/read-manga/shinobu_kokoro_wa/
http://www.mangago.zone/read-manga/hana_shinobu_no_koi/
http://www.mangago.zone/read-manga/ai_no_konseki_yajuu_gunsou_to_aigan_guni/ (2nd story)

Yesterday I asked a similar question and I received a lot of recommendations, so if you wanna check it out:
http://www.mangago.zone/home/mangatopic/980428/