Dayu

Dayu appeared in 2011 TV series called Power Rangers Samurai. Dayu (formerly known as Dahlia) was a human/Nighlok and one of Master Xandred's two followers, working to bring the Netherworld onto Earth by flooding the Sanzu River. Dayu had many powers and abilities such as, mouth blasts, super speed, basic teleportation it was seen when she was battling Mia, Dayu is also capable of creating from earth to the Netherworld.

Prior to her service to Xandred, Dayu was once a woman named Dahlia, recently married to the man known as Deker. On the night of their wedding the two presented each other with gifts; a Katana for Deker and a decorated guitar for Dahlia. Sometime in the night a fire broke out in their home while Dahlia and presumably Deker were asleep, when Dahlia woke to find their bedroom burning, Deker was nowhere to be found. The couple managed to escape the house, but Deker was severely injured.

In a moment of desperation she called out for help and summoned the "King of the Nighlok's" (later revealed to be Serrator). Serrator agreed to save Deker, but at the expense of Dahlia's humanity. She agreed to his terms and was tricked soon thereafter, Serrator turned them both into Nighloks and wiped Deker of his memory. Upon Deker's revival and immediate transformation into his Nighlok half, he vanished, leaving Dahlia behind. She then was transformed into her current Nighlok form of Dayu. Some unknown amount of time later, Dayu was approached by Master Xandred, who was drawn to the sad music Dayu played on her transformed harmonium, as it soothed his uncontrollable rage and painful headaches. He offered her a place as his minion, which she accepted.

As a half-Nighlok, Dayu served as one of the two generals working at Xandred's side to fight against the Samurai Rangers, yet she is embittered by her time in the Netherworld. Dayu still clings to the memory of her mortal life and her relationship with Deker, despite that he has no memory of their life together. She primarily regrets "cursing" him as a Nighlok with the unquenchable desire for the "ultimate duel". On one occasion, she attempted to use the tears of newlywed brides to flood the Sanzu River and recreate her wedding dress, only to be foiled by the Samurai Rangers (Miaand Emily in particular).

She is skilled in battle, lasting long enough against the Rangers until Jayden prepared to attack her with the Fire Smasher. It was there that she was rescued and forced to retreat by Deker, who intervened in the battle upon finding the opponent Uramasa (his Katana) was seeking. She thanks him for saving her life and inquires why he wishes to fight the Red Ranger, to which he answers he is "cursed to satisfy this urge" for the ultimate duel and nothing else was important, not even his past life.

When visiting The Tengen Gate, Mia and Kevin were told of the old folktale about a woman who made a deal with the King of the Nighloks to save her beloved and was tricked, foreshadowing the fate of Dayu and Deker. When Xandred damaged her Harmonium, Dayu fled the ship, intending not to return. She attacked a guitarist performing for the public, intending to use him to repair her weapon. This incites a battle between her and Mia, who happened to be passing by when she attacked. Xandred sends Rhinosnorus after Dayu, the monster blasts them with a sleeping spell and the two are sent into the dream world where Dayu's past life is revealed to the Pink Samurai Ranger.

Dayu later finds the Furry Wart that was cast out by Master Xandred. She now has someone to talk to at last. Dayu tells the Furry Wart that Master Xandred had broken her harmonium and wants revenge for it.

Dayu thought Deker was dead. She went to the spot, where she thought he had perished, only to find his broken sword. There, she encountered Serrator once again. She was still mad at Serrator, after what he did to her and Deker in the past. Serrator offered to fix her Harmonium, and locate Deker, if she agreed to serve him, which she did. She later finds Deker in the woods. Deker revealed to her that his Ultimate Duel didn't free him from his curse, due to his sword being broken. Dayu convinced him to join Serrator, in exchange for fixing his sword, which he did. When they joined forces with Serrator, he gave Dayu a dagger as a temporary replacement and Deker a Mooger's sword as a temporary replacement too.

Later, Dayu returned to Master Xandred's side, after he fixes her Harmonium. Before this happened, she was betrayed and attacked by Serrator, who revealed that she was merely a pawn in his own master plan.

Some time after Serrator betrayed her, Dayu tried to convince Deker to join with her and Master Xandred, having completely lost all trust in Serrator. Her fears are further convinced, when she saw Serrator give Deker back his sword, while she silently hoped that Deker won't allow Serrator to use him as a pawn. When Serrator was locating the weakest point between Earth and the Netherworld, Dayu followed him there. When Deker arrived to claim Uramasa, Dayu watched as Deker betrayed Serrator, in a mix of relief and concern. Later, after Serrator's destruction, Dayu went to Deker's side, offering to help him find a way to break his curse. After he denied her assistance, she returned to Octoroo on the Netherworld ship.

Later when, Deker and Jayden were fighting each other, Dayu sensed that Deker and Jayden are fighting each other in an epic duel. During nighttime, Dayu tried to stop Deker from continuing the duel because she doesn't want to lose Deker again. Since Deker refused and stated that he wants to be freed from his curse, Dayu reluctantly let Deker continue the duel. When Deker died, Dayu planned to spread misery in the human world. She fought with Mia who broke her harmonium causing Master Xandred to return. After Xandred returned, he thanked Dayu for reviving him, but she stated that she played the harmonium for Deker. She further explained that she wasn't really a nighlok due to her heart remaining human. Reminded of that, Xandred absorbed Dayu to gain immunity from drying out and the Sealing Symbol. If Dayu was still alive in some form following her absorption, then she too was killed when the Samurai Rangers defeated Xandred, possibly allowing her to be reunited with Deker in the afterlife.

Self-confident, callous, and arrogant, Dayu keeps mostly to herself, interacting with Octoroo and Xandred only when spoken to or during other needed times. She is also quite antagonistic to others, often insulting the Nighlok that shows up on the ship. Xandred and Deker are the only ones she shows any respect for. However, underneath all her arrogance and scorn is actually a sad and tormented woman who lost everything she loved, and who would do anything to get some semblance of that life back. She holds a desperate attachment to her harmonium, as it is the only reminder of the happiness she once had. Her time as a Nighlok has also made her quite bitter, attacking Mia even after she showed her compassion for her plight. She also holds a great deal of guilt over Deker, feeling responsible for his cursed half-Nighlok existence, and wants him to be free of it.

Arsenals
Dayu's guitar, the "Harmonium" (transfigured into a shamisen) serves as her primary weapon, the headstock of the instrument conceals a short sword, with the headstock acting as its hilt. According to Master Xandred, the "Harmonium" soothes him, as it's music is a song of despair. Only Dayu's song, while performed and played using this instrument, can soothe Master Xandred and his chronic headaches.

After agreeing to help Serrator with his schemes, he gave her a special dagger-like weapon to use while he took her damaged instrument.