Timelesz Drops Theme Song for Live-Action My Sister's Boyfriend; Trailer Reveals December 4 Release

Urgent: Timelesz’s New Theme Song Lights Up the My Sister’s Boyfriend Trailer

The moment the 60‑second trailer for the live‑action film My Sister’s Boyfriend dropped on Thursday, anime communities erupted. The short clip not only teased the film’s opening scenes but also premiered the group timelesz’s fresh track, “Hontō no Koto o Iu to” (If I Tell the Truth). With the film slated to hit Japanese theaters on December 4, the timing couldn’t be more perfect for a surge of buzz.

What We Know

• Film: My Sister’s Boyfriend (English title), live‑action adaptation of Amu Meguro’s manga Midori Loves My Sister (Onē‑chan no Midori‑kun).
• Release Date: December 4 in Japan.
• Theme Song: “Hontō no Koto o Iu to” performed by idol group timelesz.
• Lead Cast:
  • Masaki Hashimoto (from live‑action Summer Complicity) as Midori Yukishiro.
  • Runa Nakajima (Uchi no Otōto‑domo ga Sumimasen) as Sui Sanae.
  • Rinka Kumada (Otonanajimi, Kimi ni Todoke) as Momo Sanae, Sui’s older sister and Midori’s girlfriend.
  • Reo Matsumoto (I Cannot Reach You, Propaganda Game) as Ayame Mizukawa, Sui’s childhood friend.
  • Taisuke Niihara (At 25:00 in Akasaka, Young & Fine) as Amamiya, a new assistant producer.
• Crew: Directed by Mahito Kimura (known for Strobe Edge, Blue Spring Ride series); script by Nami Kikkawa (Honey Lemon Soda film).
• Production & Distribution: Shochiku handled planning, production oversight, and distribution.
• Manga Background: Created by Amu Meguro, serialized in Shueisha’s Bessatsu Margaret starting in 2022. The 11th compiled volume was released on April 23. Meguro’s earlier works include Hinata no Blue (ended July 2021) and Honey So Sweet (August 2012‑November 2015). Viz Media’s Shojo Beat imprint released the manga in English.

Why Fans Are Excited

The announcement hits multiple high‑impact points for the anime‑and‑live‑action fanbase:

1. Timelesz’s Rising Star Power – The group’s involvement as the film’s musical backbone brings an energetic, contemporary vibe. Fans of the idol group are eager to hear how the song complements the on‑screen romance.

2. Masaki Hashimoto’s Casting – Known for his role in Summer Complicity, Hashimoto’s portrayal of Midori Yukishiro is highly anticipated. His transition from idol to lead actor adds a layer of intrigue.

3. Fresh Visuals – The trailer’s character posters and 60‑second sneak peek provide the first visual confirmation of how the manga’s quirky dynamics will translate to live‑action, sparking speculation about the film’s tone and style.

4. December Release Window – With a holiday release, the film is positioned to capture a large domestic audience. Fans are already discussing potential box‑office performance and the opportunity for a possible international streaming deal.

Background: From Page to Screen

Amu Meguro’s Midori Loves My Sister is a coming‑of‑age romance that follows third‑year junior high student Sui as she navigates the awkwardness of her older sister’s boyfriend, Midori‑kun. The manga’s charm lies in its blend of everyday school life and the unexpected tenderness that emerges when Midori‑kun becomes Sui’s tutor. The story’s relatability has earned it a dedicated fanbase, prompting Viz Media to license the series for English readers.

The live‑action adaptation, announced in March 2018, has finally reached its climax with a full‑length film. Shochiku’s involvement signals a commitment to high production values, while Mahito Kimura’s directorial pedigree suggests a faithful yet polished adaptation. Nami Kikkawa’s scriptwriting background promises a dialogue that balances humor and emotional depth.

What’s Next

While the trailer and theme song release are the latest updates, several logical next steps emerge:

• Full Trailer Release – Fans can expect a longer, full‑length trailer in the coming weeks, likely featuring more character interactions and a deeper glimpse into the film’s narrative arc.

• Promotional Events – Given the involvement of a popular idol group and a well‑known cast, we anticipate a series of press events, fan meetings, and possibly a live‑streamed premiere party.

• Music Video – A music video for “Hontō no Koto o Iu to” could be released to coincide with the film’s opening, providing additional promotional synergy.

• International Licensing – With the manga already available in English, distributors might seek rights for overseas releases, especially in regions where live‑action adaptations of manga enjoy strong viewership.

Closing

The 60‑second trailer and timelesz’s new theme song have ignited a wave of excitement across the anime community. As December 4 approaches, fans are poised to witness how a beloved manga’s heart‑warming story will unfold on the big screen. Stay tuned for more updates, and get ready to experience My Sister’s Boyfriend like never before.