|This article is about a/an ally in Kamen Rider Build.|
Sawa Takigawa (滝川 紗羽 Takigawa Sawa) is a 27-year-old journalist who seemingly discovered Sento Kiryu's identity as Kamen Rider Build and assisted him in the investigation of Faust. But in truth, she was revealed to be a spy for Juzaburo Namba and a member of the Namba Children, but defected to and the rest of Team Build after finding a familial sense with them. She once became one of Faust's experimental victims, becoming the Stretch Smash (ストレッチスマッシュ Sutoretchi Sumasshu), was used as the basis for the Octopus Fullbottle.
Sawa grew up in an orphanage as a member of Juzaburo Namba's children. Like most of the Namba Children, they are heavily trained spies and have undying loyalty for him. If their position as spies were to ever be compromised, they would commit suicide to avoid revealing anything about Namba.
In Sawa's false backstory, she claimed her father was a researcher working for Namba Heavy Industries who died in a gas explosion that was supposedly set up by the Touto government to cover up the loss of a Pandora Box in Faust's possession. Sawa's assumed motivation in order to find out the truth behind her father's death as a Namba spy to prove a connection between Namba and the Touto government.
Sawa came to Gentoku Himuro for information about the Smash, as well as his thoughts on the rumored Kamen Rider. Much to her disgust, Gentoku merely suggested "continuing the conversation" at the nearby hotel. Later that night, Sawa herself was saved from Needle Smash by Kamen Rider Build. On orders from Namba, Sawa followed Sento to nascita, but waited to reveal her discovery.
The next day, she visits the hideout after Soichi accidentally left their hideout door open. Pretending that she found them after Sento dropped a card for nascita, and promises not to reveal Sento's identity on the condition that he gives her an interview. Later she gets them a photo of Nabeshima, the lead suspect in Ryuga's framing case.
After photographing Build's battle with the Flying Smash (and annoying him with her excited commentary), she joins Ryuga in traveling to Seito via smuggling ship to rescue Nabeshima's wife and daughter from Faust. They escape Faust Guardians and bringing them back only to discover that Faust experiments have erased Nabeshima's memories, but the family vows to make new ones.
She later tracks down Tatsuya Kishida, Sento's roommate and bandmate from before his amnesia.
Her true allegiances are revealed when she secretly provides Juzaburo Namba with photographs of all of Build's Best Match forms thus far, seemingly not for the first time. They discuss the plan for Faust to steal the Pandora Box, which will put Seito and Hokuto on high suspicion, forcing the Touto leader to prepare for war by adopting the Kamen Rider System. However, Misora finds the audio-recording bug Sawa had planted in the hideout.
She soon discovers that her bug is missing, and is noticed by Misora as she attempts to look for it. As Sawa attempts to leave, Misora confronts her, and she unsuccessfully tries to pass the bug off as just a habit for her reporting; however, she manages to slip away when Ryuga arrives, Misora being unwilling to reveal Sawa's suspicious activity just yet. Sawa reports her compromised cover to Namba, but is quickly intercepted by Faust and turned into the Stretch Smash, which was recorded on video and sent to Sento. Let loose in the city, Build KeyDragon tries fighting her, but the Dragon Fullbottle's power is too much for his body and cancels the transformation. After Ryuga manages to become Cross-Z, he defeats the Stretch Smash in one blow, but she is left on the sidelines until after Night Rogue is fought off, with Sento extracting her Smash essence. Realizing what had happened, she admits to having been a spy.
Back at nascita, Sawa reveals her true motives as a spy to Sento and gang, along with a conversation between Namba and Night Rogue she secretly recorded using a voice recorder within her necklace. After she provided information on the Pandora Box's current location, she was later chained to a chair at Sento's lab to prevent her from escaping. As Sento and Ryuga went to investigate, she told Misora about the incident regarding her father. She was later unchained by Misora when the two Riders returned.
Sawa, having taken a picture of one of the Box's panels, went to visit the hospitalized Taizan Himuro in a bid to convince him that there is connection between Faust and the Touto government. However, after Taizan received information that the government is launching an operation to wipe out Faust, Sawa's report was disproved on the spot. Two security officials were immediately deployed to arrest her, though she was able to escape.
Sawa and Sento later witnessed Touto's operation to take down Faust, where Nariaki Utsumi was seemingly exposed as "Night Rogue" and Faust's creator, before being gunned down by Gentoku Himuro. Regrouping at nascita, they found out that all the evidence gathered from Faust's hideout pinned everything onto Utsumi, with no implication of any involvement by Touto or Namba. Having believed that her job was done and that she was no longer needed, Sawa decided to leave, though she was persuaded to stay and continue helping Sento and the others, which she gladly agreed.
Alongside Misora, Sawa was a spectator at the proxy battle between Build, representing Touto, and Grease of Hokuto. Learning that Misora was holding Sento's killswitch which would break the Hazard Trigger at the cost of his life, Sawa rushed back to Nascita where she urged Banjo to intervene, leading him to save the lives of both Kazumi and Sento.
During the Build Annihilation Plan, both Sawa and Misora were among the Japanese populace whom had been compelled by "Kengo Ino" to eliminate Sento. Eventually, however, they were freed by the influence of Vernage.
After Evolto's demise, the new world was successfully created. This world's version of Sawa now works for Central Political News. She approaches Gentoku to have an interview, in which he accepts and will discuss with her later over dinner in his office.
Eventually as the alien Killbas forces Ryuga to open Pandora's Box with the white Pandora Panel, memories from the old timeline resurfaced in Sawa's mind, due to her exposure to the Nebula Gas. She and the rest of Team Build reunited with Sento and Ryuga.
Months after the incident with Killbus, Sawa received a call from Gentoku that he alongside Shinobu, Taizan, and the rests of the scientist got ambushed by Down Fall via loudspeaker indirect call. Sawa proceed to Sento and later saved Gentoku, giving him an elixir which is extracted from the customized Three Hokuto Crows to allow him to transform after he had his Hazard absorbed. After the war ended, Sawa is revealed to share Gentoku's outfit hobby and dated with him, especially the one who told Gentoku to shave.
Sawa is an enthusiastic and energetic woman, whose often bubbly demeanor masks her passionate and shrewd nature.
Having been indoctrinated as a member of the Namba Children, she also seems to have somewhat of a scheming and manipulative side. Her interactions with Sento and team would eventually warm her up, as she felt a sense of family with them which she had always yearned for. This would eventually lead her to defect from Namba's side.
- Sento Kiryu: Sento rescued her from the Needle Smash, eventually leading her to Nascita where Build's HQ is. She offers herself a place in their group, offering them secrets of all the events happening in the war. But Sento soon learns she's a spy for Nanba, not only turning back to normal from her state as Stretch Smash, but also after she tried to steal schematics of Sento's FullFullBottle designs, After all the sins she's done, she remained a full member of Team Build.
- Ryuga Banjou: She and Banjou get along helping him during his fugitive time. She helped discover Ryuga's DNA being alien relating to Evolto.
- Misora Isurugi: Both Sawa and Misora share a sisterly relationship. Regardless of how she was still a spy for Nanba, she still forgave her and took her back. Sawa comforted her for Kazumi's death.
- Kazumi Sawatari: After the Touto-Hokuto war, Sawa tries to keep Kazumi's fanboy attitude to Misora at bay, getting him to pay expensively as permission.
- Gentoku Himuro: Met him at Touto base for an interview. As now Kamen Rider Rogue, she helped restore him to health revealing her connection to Utsumi. Both Gentoku and Sawa are currently in a romantic relationship together by the time of Kamen Rider Build NEW WORLD: Kamen Rider Grease.
- Nariaki Utsumi: He along with Sawa were members of the Nanba Children. He contacted her revealing himself infiltrating Evolto's ranks to gain the Evol Driver, asking her to bring Pandora's Box to gain an advantage against the Hell Bros clones.
- Evolto: Enemy to Team Build.
- Juzaburo Namba: Who once served under him as one of the Nanba Children, till she finally leaves him for Team Build, after all the kindness and love they gave her during her time with them.
- Soichi Isurugi: Worked alongside him and Team Build until revealed not only being Blood Stalk, but also being possessed by Evolto.
Behind the Scenes
- She shares the same surname as Sora Takigawa/Gremlin from Kamen Rider Wizard.
- Coincidentally, both Sawa and Gremlin are traitors in their respective series' opposing sides: Sawa is a spy working for Namba, only to defect back to the heroes' side. While Gremlin is a renegade Phantom whose sole purpose trying to "regain" his humanity. Both of their monster forms are green.
- She is similar to Reiko Momoi from Kamen Rider Ryuki in terms of their occupation as journalists in their objective to gain information in regards of the events in their respective series.
- The Stretch Smash suit is a modified version of Mirage Smash's suit.