Saeko Sonozaki is a major character and recurring antagonist in the tokusatsu series Kamen Rider W. As the eldest daughter of the Sonozaki family, she plays a pivotal role in the operations of the Museum, the organization distributing Gaia Memories throughout Fuuto. Saeko transforms into the Clay Doll Dopant using the Clay Doll Gaia Memory, granting her formidable powers and regenerative abilities. Her complex relationships, ambition, and rivalry with her younger sister Wakana drive much of the series’ intrigue and conflict.