Magne Warrior / Yatori(Hikaru Kurosaki), a character introduce in Episode 35 & 36 and never mentioned again.Yamamori is considered a prototype of the "sixth warrior" additions featured in later Super Sentai shows.But if me, i count him as the Sixth Ranger because his appearance is big.The suits similar to Space Lone Wolf VRV Master.
Shota Yammamori : A protector of nature who lives in Mt. Nekura by himself. When the Bioman team first encounter Yamamori, Shiro ponders the possibility of whether Yamamori might carry Bio Particles within him. After falling in love with Jun, Yamamori tries to join the team desperately, but is ultimately rejected when the Bio Robo finds no traces of Bio Particles within his body. Disillusioned, Yamamori is tricked by a disguised Farrah into undergoing a procedure that would transform him into the Magne Warrior, which puts under Gear's control. However, Yamamori manages to break free of Gear's influence and helps the Bioman team destroy the Magne Megas.
He only appeared in episode 39. He was the prototype Maskman. X1 Mask is considered a precursor to the "sixth warrior" additions featured in later Super Sentai shows.His appearance only to help the Maskman and then disappear.But i still count he is the Sixth Ranger. The suit same like Battle Fever J theme costumes.
Ryo Asuka : A former disciple of Chief Sugata who was chosen to be part of the M-Project, which gave him the ability to transform into X1 Mask , a predecessor to the main Maskman team. However, Ryo abandoned Sugata's unit after his girlfriend Yūko was killed during an ambush by Tube, causing Ryo to doubt his ability to protect the world since he was unable to protect the woman he loved. Ryo arrives to help the Maskman team when they are overpowered by Magma Doggler. With Takeru's help, Ryo regain his self-confidence and assists the team in defeating Magma Doggler, but at the cost of his powers. At the end, he leaves the Maskman team to teach martial arts to children with a renewed sense of hope. As X1 Mask, Ryo wears a green-clad outfit with a white scarf and a face-like helmet with a visor for each eye.
source: Henshin Grid and SUper Sentai Blog