Ryouzanpaku are a fighting group of martial artist that was hired by miss Marple during the Koyuki's route introduced in the sequel Maji De Watashi Ni Koi Shinasai! S. According to Cookie 4, Ryouzanpaku are descendants of heroes are all considered legends. The employing mercenaries group had existed for approximately 1,000 years ago til today.
Their base lies deep in the mountains and dark valleys of china. Though it's name has been scratched off from history they are still active. Working as mercenary's from the past till now at the present times. Their system of passing down has succeeded from generation to generation. The heroes also kept the strength and the purity of their techniques.
Naoe Yamato and Shina Miyako only become part of the Ryouzanpaku in an alternate route in Rinchuu's route in Majikoi A-4
For more info : Ryouzanpaku