Beginning in 2024, Konosuke introduced a closely related sequence of knives that may be understood as a single developmental series of in-house sharpened and finished knives: the KS-01, followed by the LI, and culminating in the BY.

KS-01, LI & BY Years Made KS-01 2024-2025 LI 2025 BY 2025-Present Blacksmith Yoshikazu Tanaka Sharpener In-house (Un-named)

Marking Patterns K-F-04 K-BY-01

The KS-01 gyuto was announced in September 2024. Forged by Tanaka and sharpened and finished in-house, it was described as:

The KS-01 gyuto combines classic details with modern finishing techniques. We have taken iconic details from our flagship Fujiyama series and elevated them with a new modern approach to sharpening that has given us the ability to reach higher levels in detail and accuracy.
-Konosuke, Instagram

With the KS-01 being sharpened in-house, Konosuke would buck the long held tradition of Sakai knives being created through division of labor. Rather than knives being sent out to a sharpening specialist, the KS-01 would be sharpened by Konosuke employees trained in special sharpening techniques. The “semi-Kasumi” finish on the KS-01 would later be designated a signature feature of a Konosuke.¹

The LI entered circulation in early 2025 as a direct continuation rather than a departure. While maintaining the same underlying blade geometry and forging lineage, it introduced incremental refinements in finish and execution.

The BY, released in July 2025, completes the sequence (so far). In Konosuke’s own description, it represents a further evolution of the finishing process established in the LI. The underlying blade remains consistent across all three models, reinforcing that differentiation within the series is driven primarily by finishing methodology rather than changes in forging or profile.

All three share a consistent marking structure: chiseled kanji throughout, with steel type indicated on the left face and Konosuke inscription on the right. And with the entirety of manufacturing of the knives in the series being done in Sakai, the Sakai kanji is also present. This continuity in marking provides a stable reference framework for attribution within the series.

BY Kokuin

On November 28, 2025, Konosuke disclosed, on their subscription blog², the development of a new kokuin for the BY line. Because LI and BY knives share the same base blade—with finishing as the primary differentiator—there was concern they might become difficult to distinguish over time.

The newly developed stamp draws on the concept of Baka no Yama (“Mountain of Fools”), from which the BY designation is derived. Following several weeks of iterative design, the finalized BY kokuin was presented on January 7, 2026.

In execution, the BY kokuin aligns with contemporary Konosuke stamping practices, comparable in intent to the Myojin kokuin. It functions not merely as a decorative element but as a formalized identifier, resolving ambiguity within the series while reinforcing the conceptual framing of the BY line. As a result, BY knives now exist in both pre-stamp and stamped variations.

By July 2026, BY knives bearing the kokuin had begun appearing at the Konosuke storefront in Sakai.

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1. On March 31, 2026 Konosuke announced the release of the GH No. 18 “Grind Horse” knife. An exclusive version of the knife, available to Membership Program Members, would have a special semi-Kasumi finish first created on the KS-01 and considered a signature feature of Konosuke. ↩︎
2. Konosuke Membership Blog “No.289 Employee Engagement (3)” ↩︎