Sadatsugu Nagaishi  

, 永石 定嗣

Nagaishi is an essential ally to the three sisters, acting as their trusted friend and confidant. He possesses extensive knowledge about Cats Eyes' operations and can offer valuable insights during their heists. Furthermore, he assists them in obtaining any hardware or sophisticated equipment that Ai cannot provide. Despite his background remaining a mystery, Nagaishi's military expertise may have played a role in his abilities.