Gyokushin-ryu Ninpo Happo Biken (jewelled tiger school).
This ninjutsu school was founded by Sasaki Goroemon (4th soke of Gyokko ryu), and its speciallies are Koppo, Jutaijutsu, Ken (sword) and Iai (sword drawing). Little is known publicly about the techniques, but it is known that the focus was espionage applications rathern than combat.
The current soke is Masaaki Hatsumi