Eboya Yuzen Tanshin True Heart Eyedropper or Converter Fountain Pen
Eboya is Japan’s last remaining ebonite manufacturer. Each pen reflects a deep commitment to traditional craftsmanship and technical innovation. Ebonite—one of the earliest polymers—results from vulcanizing natural rubber with sulfur (25% to 50%), and is valued for its durability, natural shine, and warmth to the touch. Every piece is engraved with Eboya Made in Tokyo, a true mark of authenticity and excellence.
Design and inspiration
Yuzen means “to gush forth, to flow strongly.” The name was chosen to evoke the image of ideas springing like a fountain of ink, flowing into fluid writing. The Tanshin True Heart edition stands out with its deep red tone, symbolizing energy and authenticity. With a diameter of 13.6 mm—identical to the Natsume and Houju medium-sized models—it provides both stability and ergonomics. While it may appear slim, its solid construction gives it a surprisingly robust and comfortable feel in the hand.
Functionality and filling system
The Yuzen features an innovative eyedropper system that allows the body of the pen to be filled directly with ink. Its capacity of up to 3 cc makes it an ideal choice for heavy writers who seek extended autonomy. Filling is straightforward:
- Open the pen body by removing the nib section (photo 1).
- Fill an eyedropper with ink (photo 2) and pour it directly into the barrel (three drops equal about 3 cc).
- When refilling, it is recommended to wipe any residual ink inside the barrel to prevent leakage.
- If changing ink, rinse the interior thoroughly with water before use.
In addition, the Yuzen offers a dual-use option: it can also be used with standard international cartridges and converters, exactly like the other Eboya models. This versatility makes it practical for those who prefer a more conventional filling method. Pelikan cartridges are especially recommended for compatibility.
Package contents
• Eboya Yuzen Tanshin True Heart fountain pen
• Standard international converter
• Ink cartridge (1 unit)
• Eboya enhances the presentation of its fountain pens for Inktraveler, protecting them with a premium paulownia wood case, traditionally used in Japan to preserve the finest writing instruments.
• Warranty
(Photos are for reference and may slightly differ from the final product.)
Technical specifications
- Body material: ebonite
- Colour: deep red (Tanshin True Heart)
- Total length: 139 mm
- Body diameter: 13.6 mm
- Eyedropper capacity: approx. 3 cc
- Nib: 14K gold
- Filling system: eyedropper, cartridge or converter (international standard)
- Made in Tokyo, Japan
Care and maintenance
Avoid prolonged exposure to sunlight or humidity. Store in a cool, dry place. Clean occasionally with a soft cloth. When using the eyedropper system, rinse the barrel before changing inks to maintain performance.
Brand history and philosophy
Eboya is the flagship brand of Nikko Ebonite Manufacturing, founded in 1952 and known as Japan’s last ebonite specialist. For decades it supplied this material to leading pen makers such as Sailor and Pilot. In 2009, it launched its own line of fountain pens, combining technical expertise with refined Japanese aesthetics. Today, Eboya continues to craft durable, comfortable writing instruments with unmistakable craftsmanship.
"A pen that flows like a spring of ink, offering versatility and beauty in every stroke."
