Iga strongest shinobi. He lives to fight strong opponents. Oboro received hellish training and difficult missions for 15 years and wanted to fight Nobunaga to be known as the strongest, but Nobunaga was betrayed little before he meets him. He was hired to kill Harima, but ended serving him for 1 year, hoping he will find someone strong while travelling with him.

He is Rai's devoted servant and has loyally served him for over 800 years. He is a genius scientist, whose abandoned research notes helped to bring the Union's scientific knowledge and technology to the advanced level it has reached in the series. Frankenstein is also the founder and current principal of Ye Ran High School, where he is known to all as Principal Lee. He is now the latest addition to the RK-5 bearing the title of Number 0.