Japan's Y'2 Leather was founded in 1998, by artisans with over 45 years of experience in the manufacturing of leather jackets. Since then, they've been producing some of the very best and most unique leather goods in all of Japan, working directly with tanneries to produce fully custom and unusual leathers of the highest quality to pair with each new style.

Their decades of knowledge collide with these custom leathers on the workshop floor, where Y'2 Leather can blend vintage techniques and styles with modern sensibilities to create familiar silhouettes in new and exciting materials.

The Kakishibu Type-I Jacket is a spectacular example of Y'2 doing what they do best, reimagining a classic style in an incredible custom horsehide that looks stellar from day one and ages quickly and drastically. The leather itself is difficult to produce and sensitive to work with, as this isn't just any natural (undyed) veg-tan leather, this horsehide is tanned and dyed with persimmons.

The leather is a Kakishibu horsehide - Kakishibu is a traditional Japanese dying technique that uses aged persimmon tannins, with "Kakishibu" literally meaning "persimmon astringency". Historically, this dying technique (which is the only dying technique culturally unique to Japan) was used on fabrics, traditional umbrellas, and occasionally for brewing equipment.

Examples of Kakishibu dyed leather can be found, but usually in the form of small goods, as the dying process is both intensive and inconsistent, meaning larger leather goods are almost never produced.

Fresh out of the box, this horsehide could be mistaken for a natural veg-tan, albeit with a bit more of a shine; and similarly to that leather, it will darken noticeably over time with exposure to light.

Kakishibu has also been called “Taiyo-zome (sun-dye)” due to the photosensitivity of the dye - areas exposed to light will grow darker and richer in tone, eventually reaching a true persimmon color. As a result of this increased photosensitivity, this Kakishibu horsehide will age faster than most natural veg-tan leathers.

This rapid patina is one of the most desirable features of Kakishibu, but makes working with the dye difficult and generally discourages makers from using it. The highly acidic dye also reacts with oxygen in addition to its photosensitivity, meaning that production needs to be as fast as it is precise to ensure consistency.

The leather also scuffs easily, and the light color of the dye means things like wrinkles or scratches appear prominently on a brand new jacket - another aspect that's fantastic for patina, but poses issues for manufacturing, as extreme care must be taken not to mark the leather in any way during production.

In addition to being more laborious to produce, Kakishibu is also more expensive than other tanning and dying methods. Kakishibu is a completely organic process, coming entirely from the tannins of the persimmon fruit, making it difficulty to control for and maintain consistency and quality - this, in turn, drives up the price.

The leather is drum-tanned, a traditional tanning process that involves rolling the hides around in large wooden "drums" - during Kakishibu tanning, the drums need to be washed and maintained more regularly than with other tanning methods, as the fully organic tannins decay more easily than other tanning mediums.

Tanneries generally have to stop all other production when working on Kakishibu leathers, as the process requires full attention and regular maintenance to execute properly. During tanning, drums must be regularly emptied out and cleaned, as the acidic persimmon tannins can break down the wood more quickly, ruining both the leather and the equipment

The finishing process for the leather is also dependent on specific meteorological conditions, adding yet another layer of difficulty to the already-complicated process. Tannery workers spend years honing their sensory intuition, as well as keeping a close focus on the weather forecast to ensure that the conditions are correct for completing the work.

Once the drum tanning process is complete, the leather is removed and the finishing process begins - this entire process must be completed in a single day, or excessive oxidation will ruin the desired final product. Persimmon tannin dye is brushed onto the hides in two coats, sealing the pigment into the leather and resulting in a rich, full color.

After this, the hides are stored in the dark, as any UV or artificial lighting will begin to alter the color of the leather. Y'2 does all the sewing for these jackets in dim lighting for the very same reason, packing each jacket into a black cloth bag for safe storage when complete (bag is included with jacket).

The pattern is minimal, Y'2 basing their design on WWII era Type-I jackets, but stripping it of the traditional embellishments like a buckle back or back pleats. This allows the leather to do the talking, showing off the impressive horsehide and Y'2's masterful cutting, and ensures more consistent patina across the entire jacket.

The front features a single open chest pocket, with the classic double pleats running up the sides of the placket. The whole thing closes up with just four donut buttons, same buttons as on the cuffs - these buttons can be a bit tough at first, but break in quickly with use.

We've found these jackets to fit very true to size. Gen wears a 40, Jeremy wears a 44, and Elliot wears a 38. They've got a relaxed fit through the chest, not wide, but also not restrictive and great for layering under. The shoulders are nice and broad, with comfortably roomy armholes and biceps, and sleeves lined with a smooth 100% nylon fabric to help the jacket slide on and off with ease.

The body is lined with a 100% cotton twill, a lightweight dark brown fabric that breathes well in warmer weather. Inside, there are two chest pockets that can be used as more secure storage than the single external pocket, a nice touch and a welcome update on the WWII-era style.

Full Specs of the Kakishibu Persimmon Tanned Horsehide Type Jacket (KB-140-T)

• 1.5mm Kakishibu horsehide
• Persimmon-tanned leather
• Persimmon-dyed leather
• 100% cotton body lining
• 100% nylon sleeve lining
• Four donut shank buttons
• Double pleated front
• Single chest pocket
• Copper rivet reinforcements
• Lowered placket
• Minimal paneling
• Two internal chest pockets
• Custom labels
• Fits true to size
• Made in Japan

From the moment you first put it on, the photosensitive Kakishibu horsehide will darken as it is exposed to light, both natural and artificial. Over time, it will deepen to the color of a persimmon, with all the depth and character of the already subtly glossy 1.5mm horsehide.

The leather is fairly stiff at first, but will relax over time and break in to the shape of your body. A pretty sturdy mid-weight leather, it's not so heavy that you'll have to fight it, but some effort will be required to get it fully broken in. You can also expect to see tonal differences in creased and un-creased areas, producing a "honeycomb" effect inside the elbows and near the shoulders.

This is without a doubt one of the most special and interesting jackets we carry, and over time will develop in a truly unique way. Probably our biggest regret in all of this, as with many of the products we carry, is that we cannot age these ourselves, and so we won't get to see the way the leather darkens in color and deepens in character over time.