The official website for the upcoming live-action film adaptation of Amu Meguro's Onee-chan no Midori-kun ( Midori Loves My Sister ) romance manga series released a teaser trailer and a poster visual today. The film is scheduled to open in Japan on December 4, 2026 . Onee-chan no Midori-kun Teaser Trailer, Poster Visual Mahito Kimura ( Ao Haru Ride , Strobe Edge drama series) directs the Onee-chan no Midori-kun live-action film, based on a screenplay by Nami Yoshikawa ( Honey Lemon Soda ). The protagonist, Midori Yukishiro, is played by Masaki Hashimoto, a member of the idol group timelesz, for whom this work marks his first starring role in a film. Meanwhile, Runa Nakashima, who won the Japan Academy Film Prize for Newcomer of the Year for her role in TOKYO Taxi (2025), is cast as the heroine Sui Sanae, nicknamed Sui. Additionally, Rinka Kumada plays Sui's sister, Momo, and Leo Matsumoto is cast as Sui's childhood friend, Ayame Mizukawa. Teaser Visual The Onee-chan no Midori-kun manga series has been serialized in Shueisha's Bessatsu Margaret monthly magazine since its April 2022 issue. To date, 11 collected volumes have been published in Japan, with cumulative circulation exceeding 1.6 million copies. The protagonist of the story is Sui, a high school girl. She is uncomfortable around Midori, who is her older sister Momo's boyfriend and seven years her senior.