Seri arrives as a shape-changing android mistakenly delivered to protagonist Takuya due to a package error. Designed as a sexual companion, she transforms her physical form to fulfill her owner's fantasies. Her abilities include mimicking the appearance of real individuals, such as Takuya's co-workers, and embodying fictional characters from other media. These transformations extend to altering her size, adopting specific fetish attributes including futa characteristics, and roleplaying scenarios upon Takuya's request. Beyond her primary function as a sexaroid, she actively aids Takuya in his personal quest to locate and connect with his idol, Nazuna Suzushiro. Her actions inadvertently facilitate a closer relationship between Takuya and Nazuna by the narrative's conclusion. She exhibits programmed obedience and dedication to satisfying her master's desires, lacking independent personal motivations or backstory beyond her artificial nature. Her role centers on enabling Takuya's fantasies and advancing the plot through her assistance in tracking Nazuna.