How to Take Home Movie Mini-Posters? BELLEMOND Launches 0.5mm-Thick Rigid A3 Clear File 'Shorimamoru-kun A3' to Solve the Viral Large-Paper Storage Problem

Fun Standard Inc. (a subsidiary of RKB Mainichi Holdings Group, headquartered in Ōnojō City, Fukuoka Prefecture, with co-CEOs Ryosuke Oya and Hiroki Sasamori) has launched a rigid clear file called 'Shorimamoru-kun A3' through its brand BELLEMOND. This product is designed to protect large A3-sized documents from bending.

This product is a 0.5mm-thick rigid clear file that allows A3-sized blueprints, certificates, sewing patterns, and mini-posters to be stored without folding.

Large documents, which may feel insecure in standard thin clear files, can now be stored and transported with confidence thanks to its firm rigidity.

Left: Standard thin file. Right: Shorimamoru-kun. With its 0.5mm-thick rigid construction, even A3 documents can be supported firmly. *Photo shows A4 size.

'Shorimamoru-kun' is currently available on Amazon and Rakuten Market (coming soon).

Amazon Official Store

Rakuten Market Official Store

Additionally, the Shorimamoru-kun series offers multiple sizes and types.

A4 size. Single-color sets also available. A4 size. Opaque black version.

Related Press Releases

"Worried about carrying important documents outside?" Newly launched thick black opaque clear file protects both privacy and documents from creasing. "Shorimamoru-kun: Carry Peace of Mind"

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"Hated seeing brochures and pamphlets crease inside my bag" The ultra-rigid 0.5mm-thick A4 clear file now comes in color for the first time, letting fans protect their favorite items in their favorite colors. "I'm the rumored rigid one: Shorimamoru-kun"

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A3 documents are inherently difficult to protect without folding

Large A3-sized documents can be stored flat. Interior dimensions: W310mm × H430mm. Can hold approximately 30 A3 sheets.

Due to their larger size compared to A4, A3 documents are more prone to bending and wrinkling during transport and storage.

• Blueprints and proposal documents used at work.
• Certificates and qualification documents.
• Sewing patterns.
• Artworks and posters.
• Newspaper clippings and large-format documents.

While there is a strong desire to keep these items crease-free and in pristine condition, many users report difficulty finding A3-compatible clear files in retail stores.

In fact, reviews of standard A3 clear files often mention: "hard to find in stores," "only available at stationery specialty shops," and "want to store A3 without folding."

Furthermore, due to their large surface area, thin clear files tend to bend when documents are inserted, creating another challenge.

A rigid 0.5mm-thick solution for large documents that feel insecure in standard thin files

Compared to standard thin files, the 0.5mm-thick 'Shorimamoru-kun' features a firm, rigid construction that supports the storage and transport of large documents. *Photo shows A4 size.

'Shorimamoru-kun A3' is a rigid clear file that allows A3 documents to be stored without folding.

Its standout feature is the robust 0.5mm thickness.

With greater stiffness than standard thin files, it reduces wrinkling when transporting large A3-sized documents.

The semi-transparent matte finish allows moderate visibility of contents.

Resistant to fingerprints and stains, it has a subdued appearance suitable for business settings.

Ideal for a wide range of uses—from submitting A3 blueprints to clients, storing certificates and qualifications, to organizing sewing patterns and large documents—both professionally and personally.

Trending on SNS: The "only option is to roll it up" problem with movie mini-posters

Mini-posters and promotional posters received at movie theaters.
Many people treasure them but struggle with storage: "I don’t want to fold it, but I don’t have a flat file that fits."

On social media, ideas like storing movie mini-posters rolled around plastic wrap cores have gained attention, reflecting a strong desire to preserve large paper items in good condition.

However, rolled storage can leave permanent curling when unrolled.
While not worth framing, users still want to avoid creases.
For such cases, an A3-compatible rigid clear file serves as the perfect middle-ground storage solution.

Three key features to protect paper items you don’t want to fold

Even when carried in a bag, it reduces wrinkling of large documents. Ideal for carrying blueprints and materials in pristine condition. *Bottom photo shows A4 size.

1. Rigid 0.5mm-thick construction that stands “pin” straight

When placed in thin files, large A3 documents can cause the entire file to bend.
This product uses 0.5mm-thick rigid PP material, offering firm support that’s even usable as a writing pad.

2. Large size that accommodates A3 documents without folding

Interior dimensions: W310mm × H430mm. Exterior dimensions: W315mm × H435mm.

A3 paper can be stored flat, making it ideal for storing blueprints, certificates, qualification documents, sewing patterns, posters, newspaper clippings, and other large-format documents that won’t fit in A4 files.

Can hold approximately 30 A3 sheets.

3. Designed for easy insertion and organization

Notched design allows smooth insertion and removal of documents.

Stands upright easily, enabling neat organization on shelves or inside bags.

Features rounded corners for comfort and safety when handling.

For those who want to keep blueprints, certificates, and sewing patterns in pristine condition

The rigid, upright-friendly design allows tidy organization on shelves or desks. Rounded corners ensure comfort during handling. *Photo shows A4 size.

Even as paperless initiatives advance, many items are still better preserved on paper, and paper itself deserves careful treatment.

Creases and wrinkles in work-related blueprints or proposal documents can negatively impact impressions.

Certificates and qualification documents should be kept in good condition for long-term preservation.

There is also demand for crease-free storage of sewing patterns, posters, and large documents.

BELLEMOND has responded to feedback such as "doesn’t fit in A4" and "standard files feel unreliable," developing the 'Shorimamoru-kun A3' with the right balance of rigidity and usability for A3-sized documents.

This is not just a file to store important documents—it’s a clear file designed to reduce anxiety around storage and transport.

Product Name: Shorimamoru-kun A3 Size

Release Date: May 2026

Size: A3 compatible

Contents: 5-piece set

Regular Price: 1,980 JPY (tax included)

Interior Dimensions: W310mm × H430mm

Exterior Dimensions: W315mm × H435mm

Storage Capacity: Approx. 30 A3 sheets

Material: High-quality polypropylene (PP)

Color & Texture: Semi-transparent, matte finish

Main Uses: Storage and transport of A3 blueprints, certificates, qualification documents, sewing patterns, posters, newspaper clippings, and large-format documents

*Price as of June 3, 2026.

Amazon Official Store

Rakuten Market Official