Tsukuyomi (Zi-O)

Tsukuyomi (ツクヨミ) is an amnesiac young woman who initially had no memory of her past before discovering her true heritage as a royal heiress named Alpina (アルピナ). Stranded in a different timeline with her memories erased by her older brother Swartz, she joins the Resistance and unknowingly receives a Ridewatch from Sougo Tokiwa that would allow her to become Kamen Rider Tsukuyomi (仮面ライダーツクヨミ). In an effort to change her apocalyptic future, she travels to 2018 with Black Woz and Geiz Myokoin in an attempt to guide Sougo away from his fate as Ohma Zi-O.

Early Life
Alpina is a resident of a different timeline where she and her older brother are members of a royal family with time powers. In 2058, she was chosen to be the successor to the throne over her brother because she was much more powerful. Her brother became jealous and used his powers to erase her memories (and name) and abandon her to die in Ohma Zi-O's timeline. She was later found by the Resistance and given the name Tsukuyomi, which she would keep for the next 10 years.

In 2068 as the Resistance continued their assault against Ohma Zi-O, both Tsukuyomi and Geiz were visited by a younger version of Ohma Zi-O from 2019 who went to fight Ohma Zi-O in his original base form, stuffing a blank Ridewatch into Tsukuyomi's pocket. The Ridewatch is later infused with Ohma Zi-O's essence after Sougo returns to 2019. After realizing that the two could travel through time just like the young Ohma Zi-O, Geiz suggests time traveling.

In a later attack, the Resistance assault Ohma Zi-O with heavy artillery, which Ohma Zi-O manages to overcome with minimal effort. After declaring that no one will be able to beat him, Ohma Zi-O clenched his fist and killed almost all of the Resistance members, save for Tsukuyomi as she was pushed to a narrow rift by the leader of the Resistance. In complete desperation, the two go forward with their plan to time travel to 2018 and observe Sougo Tokiwa.

The Birth of Zi-O
Traveling back to 2018, Tsukuyomi saves Sougo from Geiz and proceeds to show him his future in 50 years, becoming the most evil and despised demonic king in all of history. Despite her attempts however, she is unable to prevent Sougo from attaining the power of Zi-O and is hesitent to trust him, but after watching him, doesn't completely believe he will become Ohma Zi-O, something her friend Geiz disagrees with as he proceeds to transform into Kamen Rider Geiz Ghost Armor to destroy Sougo.

Just as Geiz is about to finish off Sougo, she interferes with her Time Mazine and proceeds to take Sougo back to 2018 where they find Another Build is still alive and attacking people. Eventually, she and Geiz are cornered and Sougo saves them, explaining to them that they need to go back to 2017 and destroy Another Build. They travel back and Tsukuyomi watches from the sidelines and Sougo attains the power of the Build Ride Watch and he and Geiz destroy Another Build. Afterwards, she and Geiz decide to live with Sougo at 9-to-5 and monitor Sougo as he gains more power, ready to stop him the day he becomes Ohma Zi-O.

Genius Gamer M
Sometime after the Another Build incident, Tsukuyomi and Geiz enroll in Sougo's school to monitor him closely at all times. It's during this observation that a mysterious illness breaks out and the only clue to it is a handheld game that everyone seems to had before becoming unconscious. They eventually conclude that they need to find the Genius Gamer M for help which lead them to Seito University Hospital where they meet Hiiro Kagami and learn that Emu, the one they are looking for, has been missing for a while and the only clue to his whereabouts are a handheld game console and a note written in German. After cracking the code, the team of Sougo, Geiz, and herself are transported to another world where they confront Another Ex-Aid and meet Emu Hojo, Genius Gamer M, and Kamen Rider Ex-Aid. During the confrontation, they learn that Another Riders take the existance of the original Rider away, leaving the latter with no memories of their previous adventures, but still need to deal with the situation. Sougo eventually figures out what Another Ex-Aid, Ida, is after and he and she tries to help Emu by convincing him to stop attacking innocent people to save his son. However, he is too far gone and the only recourse is to destroy Another Ex-Aid's power. Emu gives Sougo the Ex-Aid Ridewatch and watches as Sougo leaves to take care of the situation. Afterwards, everyone returns to 9-to-5 and Tsukuyomi and Geiz are told by Sougo that he trusts them and their judgement and hope to get along.

Amanogawa High School
Tsukuyomi and Geiz start looking into another incident involving the disappearance of school girls that are 18 years old and Libras. Their search brings them to Amanogawa High School, where Gentaro Kisaragi, aka Kamen Rider Fourze, attended school. Despite Geiz's insistence of keeping Sougo out of the situation, Tsukuyomi gets him involved and the three start questioning the students. During that time, Another Fourze makes his appearance as Sougo and Geiz try to defeat him but fail to do so. They are then taken in by the school's Kamen Rider Club and meet its advisor, Chuta Ohsugi, who notices Geiz's Ridewatches and gives Sougo the Fourze Ridewatch saying that Gentaro wanted him to have it. After that, Tsukuyomi does some digging elsewhere, learning about a young girl involved in the last attack on her friends, Karin Yamabuki, and eventually finds her in an abandoned building. She confronts her, trying to get answers when Masato Kusaka and Takumi Inui burst in, causing them to lose sight of her.

Eventually, Tsukuyomi and Geiz learn that Karin has been kept alive by the powers of Another Fourze finding and hunting down 18 year old Libra girls and also learn that Sakuma has been doing this for over 15 years, which explained why he was able to become Another Faiz as well. Eventually, the groups confront Sakuma and Karin and learn of their connection to Masato, being they were from the same private school, and proceed to find and defeat both Sakumas to stop him and her from hurting each other anymore.

GeizRevive's Timeline and Another Zi-O
to be added

2009 & Truth Behind Zi-O's Rise
Since Geiz was hesitating to destroy Sougo and prevent the rise of Ohma Zi-O, Tsukuyomi started to do a bit more digging into Sougo's past and learned that his desire to become king started after a tragic bus accident. Wanting to learn more, she went back to 2009 and saw Sougo prattling on about becoming a king and saving everyone. She also gets a glimpse of Another Zi-O, Hiryu Kakogawa (but thinks nothing of it). She goes back to the day of the accident and learns a shocking truth about the whole incident: The one who caused the accident and lives of both Sougo and Hiryu's parents was none other than Swartz. She attempted to save Sougo by shooting at Swartz but he blocked the shot, causing it to hit near Hiryu and knocking him unconscious. Swartz then transports all of the kids off the bus and leaves the adults to die in a horrible bus accident that Tsukuyomi would have been caught in as well if not for Tsukasa Kadoya's intervention.

Beginning Of Trinity
to be added

Worlds Collides and Final Time
After a distraught Sougo break the news about Michal Minato's death and Swartz's ultimatum, he takes Tsukuyomi, now he knew as her true name Alpina, before Tsukasa Kadoya to visit the year 2058 yet again. In there, Tsukuyomi meets her younger self again and asks about Swartz's true goal. A young Swartz then arrive to explain his goal, that is to save their world by fusing all Rider worlds into one and then destroying it. Before Swartz departs to enact his plan, Sougo reveals that Alpina is stronger than her brother, enraging him. This incident would later incite Swartz to wipe Alpina's memories and left her in the resistance to die.

Before the battle against Ohma Zi-O, Sougo would visit Tsukuyomi and Geiz before they depart to 2018. He unknowingly slipped a Blank Ridewatch to her pocket. Back in 2019, when Tsukuyomi is threatened by Another Decade, Sougo comes back and usher her to use said Ridewatch, that now become Tsukuyomi Ridewatch. Woz then tosses her a Ziku-Driver and with that, Tsukuyomi transforms into Kamen Rider Tsukuyomi for the first time.

Tsukuyomi seems to be siding with Swartz, betraying Sougo and his group. However after she witnessed Sougo’s transformation into Ohma Zi-O, she stabs Swartz to betray him from behind before being killed by her brother. Her death was avenged once Ohma Zi-O finally defeats Swartz.

Tsukuyomi, along with Geiz, Heure and Ora were revived in the new timeline, as she was seen going to the same school Sougo goes with others in the epilogue.

Personality
Tsukuyomi is a no-nonsense individual and shares relatively the same goals as Geiz, though she is prone to stopping Sougo from becoming Ohma Zi-O by not having him transform, as opposed to Geiz's idea of outright killing him. Her conviction to her ideals is great enough that she would save Sougo from Geiz when the latter attempts to kill him. After hearing Sougo's conviction of wanting to become a good king, Tsukuyomi began to trust him as she found almost no evidence that Sougo would eventually become Ohma Zi-O. However that conviction faltered slightly when Sougo acquired Zi-O II, which caused Tsukuyomi to become paranoid and begin to believe that Sougo could in fact become Ohma Zi-O. She sides with White Woz in an attempt to stop him, though she eventually defended young Sougo in 2009 from Swartz and realized the future could indeed be changed.

When Tsukuyomi discovers her temporal abilities, she became shocked and horrified over this fact, but was later able to accept for who she was now, rather than who she was before.

She is also shown to appreciate different kinds of foods, such as Shouichi's cooking and sweets, although according to Geiz, she has a preference to really spicy items.

Powers and Abilities

 * Temporal Freezing: As she is a member of the royal family (same as Swartz), Tsukuyomi shares the Time Jackers' ability to freeze time. Her ability is powerful enough to even freeze Swartz (another member of the royal family), something that both Heure and Ora cannot do as they have weaker versions given to them by Swartz. After learning to accept herself for what she was, she is able to control her ability at will, having used it to save innocent civilians from being crushed by following debris, and allowing allies to move within the confines of her time freezing. This ability may or may not be inherited. In the altered timeline, Tsukuyomi is fully aware of her powers and is able to use it to the best of its ability, though it can be easily canceled out by other Time Jackers.
 * Power Absorption: Much like Swartz, Tsukuyomi can absorb time manipulation powers from any person who possesses them. She used this to try and drain all of Swartz's powers but failed, only managing to retrieve a small fraction of her powers.
 * Energy Blade: Tsukuyomi could manifest a white energy blade from her hand for offensive purposes. She first manifests this blade when she stabs Swartz at his back before she’s, in turn, knocked off to death by her brother.

Forms
Like Zi-O and Geiz before her, Tsukuyomi transforms by inserting the Tsukuyomi Ridewatch into the right-hand side of the Ziku-Driver and spinning the Driver 360 degrees.

Devices

 * Ziku Driver - Transformation device
 * Tsukuyomi Ridewatch - Transformation trinket
 * Ridewatch Holder- Strap for carrying Ridewatches. Unlike other Riders, she has only one Holder as compared to two.

Weapons

 * Faizphone X
 * Luminous Fractor - Kamen Rider Tsukuyomi's personal weapon, which appeared to be fully constituted of light.

Vehicles

 * Time Mazine

Relationships

 * Sougo Tokiwa/Kamen Rider Zi-O: Like Geiz, Tsukuyomi believes Sougo to be the evil tyrant Ohma Zi-O and decided to go back in time to change his fate. At first, she seemed confused that a light-hearted teenager like Sougo could grow into an evil Demon King. But that quickly changes when she notices his earnest motivation to become a king and his ability to activate the Zi-O Ridewatch. Despite this, she wants to help and guide Sougo in being a hero as Zi-O so time and history can hopefully be altered for the better. But she then loses her faith in him when he becomes Zi-O II. She then reaffirms her mission to kill Sougo, even going as far as time traveling to 2009, seemingly to kill Sougo when he was still a child, while she actually protected the younger Sougo from Swartz after she learned the truth. Once discovering that Swartz was responsible for what had occurred and the possibility of Sougo's future as Ohma Zi-O could be altered, her doubt was cast aside as both she and Geiz reconciled with him and return to 9 5 DO.
 * Geiz Myokoin/Kamen Rider Geiz: Geiz and Tsukuyomi were on the side determined to defeat Ohma Zi-O in the year 2068. But after witnessing many casualties, Geiz came to the conclusion that he needs to kill the man who would become Ohma Zi-O in the past. Tsukuyomi does not agree with this but Geiz goes back in time. She tries to protect Sougo from him, believing it's not right to kill him for something he hasn't even done yet. After Geiz tries to help Zi-O, she asks him to do what he come for. Although Tsukuyomi remains allies with Geiz, she decides to settle their mission on her own. Upon learning the whole truth, Tsukuyomi later convinces Geiz to postpone his and Sougo’s duel.
 * Black Woz: Tsukuyomi was once a Resistance member under Black Woz. However, after Black Woz betrayal, Tsukuyomi distrust her former captain, although she still remain civil to him. Black Woz on the other hand become worried after Tsukuyomi shows her ability to stop time temporarily and believes that Tsukuyomi might have been a Time Jacker before her amnesia.
 * White Woz: After Sougo became Zi-O II, Tsukuyomi chose to side with White Woz in order to change the future until she learned the truth of Sougo's past and being informed by Tsukasa Kadoya that the future could be changed.
 * Swartz: Swartz is in fact her older brother, though their relationship seems to have gone estranged since Tsukuyomi lost her memories and the way Swartz has been treating her since. However their interactions increased once Tsukuyomi's time-stopping abilities were re-awakened in her teen years. Once the world starts showing signs of being destroyed, Tsukuyomi travels back in time with Sougo with the intention of killing a younger Swartz but could not bring herself to kill her brother.

Legend Riders

 * Tsukasa Kadoya/Kamen Rider Decade: Tsukuyomi was saved by Tsukasa during the bus accident in 2009. They both learn the whole truth about Sougo’s past and Tsukasa himself explained his motives to Tsukuyomi. Thanks to the knowledge, Tsukuyomi regained her faith in Sougo. He also helped her discover her past, exposing the fact that they are siblings, and that they are from another timeline.
 * Shouichi Tsugami/Kamen Rider Agito: Tsukuyomi met Shouichi while she isolated herself from her fellow 9 5 DO members due to her newfound ability to freeze time and her unknown past due to her amnesia, something Shouichi could relate to. Thanks to Shouichi's wisdom, Tsukuyomi regains her self confidence and masters her ability.

Portrayal
Tsukuyomi is portrayed by Shieri Ohata (大幡 しえり). As Kamen Rider Tsukuyomi, her suit actress is Natsumi Sano (佐野 夏未).

Etymology
Tsukuyomi comes from the moon god  of the Shinto religion and Japanese myth. Her real name is named after Alpina Watches, a watch manufacturer located in Switzerland. Alpina is also a name of a species of a white moth (Eudonia alpina) which fits her dress.