If we're talking about the quintessential "sister-type" actress, who would be your top pick? Well, there are probably a ton of different answers out there—after all, a thousand people have a thousand different Hamlets in their minds! But if we narrow the timeframe to around 2010 plus or minus five years, I personally think the question becomes pretty straightforward, especially when you factor in her overall career achievements and influence. The answer is clear: it's "Seina Nanase." As an AV actress active from 2009 to 2013, Seina Nanase not only dominated the scene with her petite build, versatile roles, and massive popularity, but she also profoundly shaped the entire Japanese AV industry. She was essentially the pioneer of the "petite type" and a prime example of the "multi-role actress," and upon her retirement, she injected fresh energy into the industry through savvy business moves, innovative content, and a successful career pivot. SACE-086, titled "Ah, I'm the Doorknob...," was released by SOD on June 21, 2012, and it's based on a legendary doujinshi. The story revolves around the simple, pure affection between a mysterious doorknob creature and its owner. Seina Nanase plays the role of "Doorknob-chan," who appears as a cute, petite girl on the outside, but her private parts transform into a keyhole—an always-open entrance waiting for "coming home" (insertion). The story of "Doorknob Pure Love" is set in an ordinary urban apartment, where the male lead is a salaryman who, upon returning home exhausted each day, unexpectedly forms a connection with this "doorknob." The film uses a first-person perspective interspersed with Doorknob-chan's inner monologues, starting with black-and-white flashbacks depicting her "birth": awakening with consciousness from a rusty old door and taking human form, yet forever bound to the doorframe. The entire film is divided into five main chapters, each corresponding to the owner's daily homecoming ritual—from the loneliness of morning waits to the intense climaxes at night, with plenty of squirting scenes woven in as emotional releases. At just 20 years old and at the peak of her career, Seina Nanase's performance in this film is a standout for its wild creativity, her incredible body flexibility, and the subtle "sense of longing" in her eyes, which helped it become a hot-selling item for SOD. Even now, AI-remastered versions are still being released, showing just how popular it was. Seina Nanase's AV career wasn't a long one, but as mentioned earlier, her influence on the Japanese AV industry is undeniable and can be summed up in three key areas: First, boosting sales and industry visibility—her debut film "Escalating Rookie Girl 146" sold over 200,000 copies right away (when the industry average was just 10,000), and her works racked up over 10 million views, which was a huge shot in the arm for the AV market, especially during economic downturns. She also won numerous prestigious awards, like the 2011 SOD Grand Prize for Outstanding Actress, the 2012 SKY PerfecTV! Adult Broadcasting Award for Actress, the Nikkan Gendai Award, and ranking 5th in the AV 30th Anniversary Poll. This indirectly increased public exposure for AV actresses and spurred cross-studio collaborations (such as with SOD, KMP, and the Universe Group). Second, expanding the narrative boundaries as a multi-role pioneer: She tackled everything from lolita, fair-skinned gal, student roles, to seductress and nurse, crossing multiple genres and revolutionizing the single-concept model. This influenced younger actresses to pursue diverse performances, broadening the audience base and encouraging non-exclusive actresses to aim for the top, ultimately raising the overall quality of industry content. Third, reshaping the image of the AV actress profession: After retiring in 2013 due to "burnout syndrome," she transitioned into a singer (lead vocalist of the band Mezcolanza, releasing albums like "MEZCOLAND" in 2016), a talent (hosting radio shows and YouTube channels with over 1.28 million views), and a spokesperson (as KMP's PR director), and in 2024, she put out a photo book "coco" to mark her 15th anniversary. This shattered the stereotype that AV actresses struggle to transition, inspiring the industry to prioritize mental and physical health along with diverse career paths. She proved that this profession can go mainstream, opening doors for AV actresses to enter broader entertainment and challenging the myth that two-thirds of retired actresses end up in the sex industry. Seina Nanase pushed AV from the fringes into the mainstream, emphasizing "diversity" and "sustainability," laying the foundation for the industry's transformation in the 2010s. Even today, her music tours and social media remain active, continuing to inspire the next generation of actresses. She's truly the queen of sales and a pioneer of reinvention.