Eboya Hakobune Tanshin True Heart Medium Fountain Pen
The Eboya Hakobune Tanshin True Heart Medium Fountain Pen combines deep red marbled ebonite with a clean, clipless silhouette. Handcrafted and polished in Tokyo, its surface moves between ruby red, burgundy and almost black depending on the light. A 14K gold nib completes a balanced writing instrument designed for regular use. It is ideal for writers who appreciate Japanese craftsmanship, comfortable proportions and materials that make every pen visibly different.
Concept and design
Hakobune (方舟) means “ark” or a boat with a rectangular form. Eboya chose the name with the wish that its fountain pens would carry happiness to the people who write with them. The model follows a traditional rounded profile without a clip, allowing the cap and barrel to create one uninterrupted silhouette and keeping the marbled ebonite fully visible.
The name Tanshin (丹心) conveys the idea of a true, sincere and direct heart. This finish expresses that character through a rich red mixture rather than a flat, uniform colour. Dark burgundy areas are crossed by brighter ruby streaks and near-black accents, creating a surface that can appear restrained in soft light and noticeably more vivid under direct illumination.
Every ebonite rod develops its own arrangement of colour. Lines, darker sections and small variations emerge during production and cannot be reproduced in exactly the same way on another pen. These differences are a natural feature of the material, making each Hakobune Tanshin an individual piece rather than a standardised pattern.
Each fountain pen is carefully made and polished by hand at Nikko Ebonite Manufacturing. This work brings out the deep lustre of the ebonite while preserving its warm, comfortable feel. The clipless design leaves the marbling uninterrupted, while the engraved words Eboya Made in Tokyo provide a discreet record of the pen’s origin.
Writing performance and filling system
Medium refers to the size of the pen body, not the nib width. At 142 mm closed, 15 mm in diameter and approximately 24 g in weight, this version has a reassuring presence without reaching the dimensions of the Hakobune Large. Its rounded shape provides a comfortable platform for everyday notes, correspondence and longer writing sessions.
The Hakobune Tanshin is fitted with a 14K gold nib, carefully checked and adjusted by the craftspeople at Nikko Ebonite Manufacturing for smooth, precise and controlled writing.
The pen accepts international-standard cartridges and converters compatible with brands such as Pelikan and Rotring. It is not compatible with the formats used by Montblanc, Waterman or Caran d’Ache. To fill from an ink bottle, unscrew the barrel, fit the converter securely and draw up the ink while keeping the nib properly submerged.
Package contents
• Eboya Hakobune Tanshin True Heart Medium Fountain Pen
• Standard international converter
• Ink cartridge (1 unit)
• Paulownia wood presentation box (a special presentation prepared by Eboya for Inktraveler in place of the standard cardboard box)
• Warranty
(Product photographs are for reference. The marbling and distribution of the red and darker tones may vary from the individual pen shown.)
Technical specifications
- Brand: Eboya
- Model: Hakobune Medium
- Finish: Tanshin True Heart
- Body and cap material: original marbled ebonite by Nikko Ebonite Manufacturing
- Colour: ruby red and burgundy with darker marbling
- Body size: Medium
- Closed length: 142 mm
- Cap diameter: 15 mm
- Barrel diameter: 15 mm
- Approximate weight: 24 g
- Nib: 14K gold
- Available nib widths: Fine, Medium Fine, Medium and Broad, subject to availability
- Filling system: international-standard cartridge or converter
- Design: clipless
- Engraving: Eboya Made in Tokyo
- Handcrafted in Tokyo, Japan
Frequently asked questions
Does Medium refer to the pen size or the nib width?
Medium identifies the size of the pen body. The writing width is selected separately from Fine, Medium Fine, Medium and Broad, subject to availability.
Will every Hakobune Tanshin have the same marbling?
No. Each body comes from a different section of marbled ebonite, so the distribution of ruby, burgundy and darker areas varies naturally. The photographs show a representative individual pen.
Which nib widths are available?
Eboya produces the Medium-size body with Fine, Medium Fine, Medium and Broad nibs. Availability may vary, so check the selectable options before ordering.
Which cartridges and converters can be used?
The pen uses the international standard and accepts compatible options from brands such as Pelikan and Rotring. It does not accept the formats used by Montblanc, Waterman or Caran d’Ache.
Does the Eboya Hakobune Tanshin have a clip?
No. Hakobune is intentionally clipless, preserving its continuous silhouette and leaving the marbled ebonite fully visible.
Can pigment inks be used?
Eboya advises against using pigment inks in its fountain pens. Standard fountain pen ink is recommended, and the filling system should be flushed with water before changing colours.
Care and maintenance
Ebonite may gradually change in tone or lose some of its original gloss. This ageing process is a natural characteristic of the material rather than a manufacturing defect. To preserve the finish, avoid prolonged exposure to direct sunlight and humidity, store the pen in a dark place and wipe the surface occasionally with a soft cloth.
Before changing ink colours or brands, flush the filling system thoroughly with clean water until it runs clear. When carrying an inked pen, keeping the nib pointing upwards can also help reduce the risk of leakage.
Eboya and the craft of ebonite
Eboya is the writing instrument brand of Nikko Ebonite Manufacturing, founded in Tokyo in 1952 and recognised as Japan’s last specialist manufacturer of ebonite. After supplying the material to leading Japanese pen makers for decades, the company introduced its own fountain pen collection in 2009.
Nikko Ebonite reserves part of its original marbled colour range for Eboya writing instruments. Tanshin belongs to this distinctive palette and treats red as a material with depth and movement rather than a uniform surface colour. The company’s experience allows it to oversee the process from producing the ebonite rods to the final finishing of the completed pen.
The Hakobune Tanshin reflects this material-led philosophy. Its character comes from the ebonite itself, the hands that finish it and the natural differences revealed across its surface. The result is both a practical fountain pen and an individual example of Tokyo craftsmanship.
"A true heart does not need to speak loudly; it leaves its character in every word."
