📋 Summary
- Hi-Lex ACT Corporation is a Japanese door lock and latch specialist with roots tracing to a press-processing shop founded in 1903, formally established as Ohi Seisakusho in 1943, and entering door lock manufacturing in 1949
- The company has changed corporate ownership and names multiple times: becoming a Mitsui Kinzoku subsidiary in 2003, merging into Mitsui Kinzoku ACT Corporation in 2010, and most recently becoming a wholly owned subsidiary of Hi-Lex Corporation under its current name in 2025
- The company is headquartered in Yokohama, Kanagawa Prefecture, and specializes in side-door latches (reportedly around 30% of its output), along with trunk, back door, hood, and seat latches, and power sliding-door mechanisms
- This is a genuinely useful example of a component specialist that’s remained continuously operating and technically focused despite multiple corporate ownership changes over more than a century
Door latches are a genuinely invisible but essential part of daily vehicle use, and the company behind them has a genuinely unusual corporate history worth understanding accurately, including its most recent 2025 ownership change.
Over a Century of History Through Multiple Corporate Names
The company now known as Hi-Lex ACT Corporation traces its roots to a press-processing shop called Ohi Kinichiro Shoten, founded in 1903, according to Japanese-language corporate sources. It was formally established as Ohi Seisakusho in 1943, and began manufacturing door locks specifically in 1949. Mitsui Mining & Smelting (Mitsui Kinzoku) entered the door-lock manufacturing business in 1966, and Ohi Seisakusho became a wholly owned Mitsui Kinzoku subsidiary in 2003. In July 2010, the company merged with Mitsui Kinzoku’s automotive equipment division to become Mitsui Kinzoku ACT Corporation. Most recently, in 2025, the company became a wholly owned subsidiary of Hi-Lex Corporation and was renamed Hi-Lex ACT Corporation, its current name. The company is headquartered in Yokohama, Kanagawa Prefecture.
💡 Tip: This Company Has Had Several Names Across Different Eras
If you encounter older parts documentation referencing “Ohi Seisakusho” or “Mitsui Kinzoku ACT,” these refer to the same continuously operating business now known as Hi-Lex ACT Corporation following its 2025 ownership change, not separate or discontinued companies.
A Genuine Door Latch and Lock Specialist
Hi-Lex ACT’s core products include side-door latches, reportedly representing around 30% of the company’s output, along with trunk, back door, hood, and seat latches, and power sliding-door mechanisms, according to the company’s own corporate materials. This is genuinely distinct from Tokai Rika, covered in a separate article in this series, which specializes in switches, seatbelts, and smart-key electronics; Hi-Lex ACT’s focus is specifically the mechanical latch and locking hardware itself, a related but different component category within a vehicle’s door and closure systems.
Parent Company Hi-Lex Brings Genuine Window Regulator Scale to the Group
Since Hi-Lex ACT’s 2025 acquisition, it’s worth understanding what its parent, Hi-Lex Corporation, brings to the combined business: Hi-Lex has supplied automotive window regulators, the mechanisms that raise and lower window glass, for more than 40 years, and now produces over 10 million window regulators annually. Hi-Lex has also developed integrated “door modules,” which combine the window regulator and door latch hardware onto a single resin carrier plate installed as one unit during vehicle assembly, an approach that genuinely simplifies the door-assembly process on the production line while improving glass movement stability and reducing both noise and weight compared to separately mounted components. With Hi-Lex ACT’s latch expertise now under the same corporate umbrella as this window-regulator and door-module capability, the combined group has a genuinely comprehensive position across nearly everything mechanical that moves or locks a vehicle door.
Why Door Latch Reliability Genuinely Matters
A failing door latch is a genuinely real safety concern, a door that doesn’t latch securely can open unexpectedly, particularly relevant for an aging JDM import where latch mechanisms may show wear. Understanding that a specialized, long-established manufacturer like Hi-Lex ACT likely engineered these components provides useful context when diagnosing or sourcing replacement parts for latch-related issues.
⚠️ Caution: Never Ignore a Door That Doesn’t Latch Securely
A door latch that doesn’t fully engage or that occasionally pops open while driving is a genuine safety hazard, not a minor inconvenience. Have any suspected door latch issue diagnosed and repaired by a qualified professional promptly, rather than continuing to drive with a door that doesn’t latch reliably.
Frequently Asked Questions
Q: Is Hi-Lex ACT the same company as Ohi Seisakusho?
A: Yes, it’s the same continuously operating business, which has changed names and ownership multiple times, most recently becoming Hi-Lex ACT Corporation in 2025.
Q: What does Hi-Lex ACT make?
A: Door, trunk, back door, hood, and seat latches, along with power sliding-door mechanisms, with side-door latches representing a significant share of output.
Q: Is Hi-Lex ACT the same as Tokai Rika?
A: No, they’re separate companies. Hi-Lex ACT specializes in mechanical latch and locking hardware, while Tokai Rika (covered in a separate article) specializes in switches, seatbelts, and smart-key electronics.
Q: When did the company start making door locks specifically?
A: 1949, following the company’s 1943 formal establishment as Ohi Seisakusho.
This article is for general informational purposes based on publicly available company sources. Always have door latch or locking mechanism issues diagnosed and repaired by a qualified professional.
Image credit: Toyota Yaris Exterior Door Handle by Bindydad123, CC BY-SA 4.0, via Wikimedia Commons
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