Full Name: Natsuki Mamiya/Lelina of the Lemuria Civilization
Ranger Designation: Bouken Yellow
Weapons: Survibuster, Surviblade, Scope Shot, Bucket Scoopers
Gear: Accellular
Gougou Vehicle: Gougou Dozer, Gougou Drill, Gougou Attacker
She is still relatively new to the team, she is the Strong Adventurer. Masumi found her a while ago when she had a rock under her leg. She is attached to him and follows him around. She sometimes has visions of the future though she is not fully aware of it. She has a mysterious past, she can't remember much of it. She often talks about herself in third person and has a cheery outgoing exterior. In Episode 2, she wanted to give up too and gave her Accelluar to Sakura. It took a while for Sakura to warm up to her. She carries a bracelet around her wrist that has gotten attention by other entities. One being Kazuko 'Nami-emon' Karamonoya, the protector of the Manuscript of Leon Giordana, who she grown attached to from Episodes 9 through 11 and Rei of the Ashu Clan which caused him to pick her to use her blood to open the Mirror of Hundred-Demons. In Episode 14, Nendogami disguised as an her supposed sister Miria and gave her a bracelet that looked like hers but it was a device to trap her and control her. In Episode 19, she, Shouta, and Satoru met Eiji's mother Kei in a mirror and Natsuki gave the crustalized form of her tear to Eiji. She refers Eiji as Ei-chan.

In Episode 33, Kazuko Karamonoya gave her a statue of a woman wearing the bracelet and holding Zubaan in his sword mode. After seeing this statue, both Natsuki and Zubaan started acting strangely. The Questers and Ryuwon kidnap Masumi and Natsuki forcing them to where Masumi found Natsuki. At the cave where flowers frow in barren land, especially a rare flower not indigenous to the area. Natsuki is the last survivor of the Lemurian Civilization. 100,000 years ago, her parents [played by Eri Tanaka (MegaYellow) and Keisuke Tsuchiya (KirinRanger)] being the leaders of the society, left their daughter Lelina in a sleeping capsule that would slow her growth speed to a rate of a year per every 5,000 years. Inside the capsule Nastuki was in, there was also the Precious known as 'The Sun of Lemuria'. When Natsuki touched the Precious, she gain her Lemurian princess dress. The Quester Rei brainwashed her into thinking that her parents' desire (and her sacred duty) was to activate the Sun of Lemuria and destroy humanity in the process. Having also obtained control over Zubaan, Natsuki was powering the Sun of Lemurian infulenced with Ryuwon and the Questers.
When Masumi finally broke into the base, he tried to bring Natsuki back from the trance Rei placed her under. After remembering who she was, Bouken Yellow, the enchantment broke and with a message from her parents that their dying wish was for her to be happy, she remained Natsuki ready for whatever her future brings. It can be speculated that whatver lifeforce energy was drained from her to power the 'Sun of Lemuria' that the Questers said will shorten her lifespan may just her have an averge human lifespan. "Natuski is Natsuki." Natsuki has since been there for her teammates, especially Eiji when he fought with the Western Ashu and turned to stone and Masumi when Yaiba encouraged the darkness within him. She was destressed when Masumi left the team and wanted go on search for him, Souta was willing to go with her but Akashi didn't permit them. When the Kraths were attacking the city, she was cornered by them and was saved by Masumi. She tried to convince him to continue fighting and she realized that her treasure was her memories with her friends. Ultimately, she continued being a Boukenger with Eiji, Souta, Zuuban and her chief Masumi.