|This article is about a/an Dopant identity in Kamen Rider W.|
The Taboo Dopant has the appearance of a rag doll and gains the ability to fly and generate deadly bombs of intensely hot light.
- Main article: Saeko Sonozaki
The main user of the Taboo Memory was Saeko Sonozaki (園咲 冴子 Sonozaki Saeko), the eldest of the Sonozaki children who rans an IT company called the Digal Corporation (ディガル・コーポレーション Digaru Kōporēshon), which serves as a front for Gaia Memory production and distribution. Ryubee strictly raised Saeko to believe that their family was superior to all others and that they were destined to rule the world. This loveless upbringing caused her to grow up secretly hating her father, often taking the resulting rage out on her younger sister Wakana, serving as fuel for her own ulterior motives of taking over the Museum to prove herself to her father to be its ideal successor. She also had a tendency to kill her boyfriends if they do not live up to her expectations. When Saeko spared Kirihiko due to his capabilities, she married him and let him live until he threatened the Museum's livelihood. She had no problems executing Kirihiko as she had never loved him. After Kirihiko's death, Saeko began to visit Shinkuro Isaka to improve her Dopant form and focus on her plans for the Museum. After he was almost defeated by the Kamen Riders, she began to show that she cared for Isaka's well-being, which was likely to be genuine attraction to the doctor. Once her coup against her father failed and Isaka was killed off, Saeko gone on the lam and was hunted down by the Smilodon Dopant, who took the Taboo Memory and left her for dead. However, Saeko was saved by Jun Kazu who offered his support in her scheme to take control of the Museum. After infiltrating the Digal Corporation, now with Wakana as its head, to obtain the Nasca Memory and then using an L.C.O.G on herself instead of using the Memory with a Gaia Driver. Without inhibitions posed by a Driver, Saeko was able to use the Gaia Memory in its Level 3 state to become the R Nasca Dopant to overpower her sister. However, when Wakana evolved to ClayDoll Xtreme, which Saeko proved to be utterly powerless against, she was forced to go after other options to make herself more powerful, such as the Jewel Memory, before the Nasca Memory was destroyed in a confrontation with ClayDoll Xtreme. Later, after her father's death, Saeko was disillusioned until she learnt of Wakana's survival and regained the Taboo Memory from Kazu after he announced that she had become the head of the Museum. However, no longer having a reason to prove herself with her father dead, Saeko fought Kazu in order to save her sister. As a result, the Taboo Dopant sacrificed herself to hold off the Utopia Dopant to give Wakana time to run away, resulting in Saeko's death as she finally admitted the irony of her last moments in her final breath.