The story of the Tensei project began early in my childhood, back in the days when Call of Duty: World at War released in 2008. Those that played World at War likely had fond memories of the Nambu Type 100, as it was widely regarded as one of the best submachine guns in the game. That was my first "experience" with the Nambu, and eventually I encountered it in other video games such as Bad Company 2, and Red Orchestra 2 - Rising Storm, and it was also present in many of the newer WW2 era Call of Duty titles. Like most firearm enthusiasts of my generation, our interest started with playing video games, and developing a fascination with interesting firearms as we grew up. 

As I grew older, I developed a strong interest in collecting and restoring vintage firearms as well as the learning the art of manual machining. In 2015, when I was around 20 years old, I began apprenticing at a machine shop where I grew up in El Segundo, California. The owner and I became fast friends, having a shared interest in classic cars, firearms, and manufacturing. My interest in restorations on old guns eventually led to me becoming interested in gunsmithing and firearms design, and I began designing and making replacement parts such as barrels and firing pins for vintage and antique guns that have long since been obsolete. At the time, I also developed an interest in converting fully automatic "parts kits" to semi automatic carbines. Such parts kits included guns like the British Sten, the Finnish Suomi M/31, and the Polish PPS-43. 

In 2017, with the Nambu still in mind, and the Fort DeRussy museum on my list of to-do's, we traveled to Honolulu for a summer family vacation. Within the museum was one of the few rare examples of a late war Nambu Type 100/44. I was lucky enough to be granted access into the museum's archives, where I collected a wealth of reference material that became invaluable later in the reverse engineering process.

Between 2017 and early 2024, not much happened with the Tensei project with the exception of a few notable instances where owners of miscellaneous Nambu parts made contact with me, and we exchanged measurements for the parts we had. By now I was confident I had most of the dimensions accurate on a 2D scale, but I still did not have much to reference to on a 3D scale with the exception of the photographs I took in Hawaii. 

In February of 2024, a friend that worked at an auction company in California reached out and informed me that they had come across what they believed to be the barreled action of a Nambu submachine gun. I gathered my measuring tools and immediately took off, and spent the next several hours taking every measurement I could think of, not knowing if I could come close to a cash offer that they would consider. After some deliberating, we came up with a number that both of us were happy with, and I walked away with something I never thought I would lay hands on - a demilled barreled action of a early serial number, late war Nambu Type 100/44. I spent the next week modeling the entire barreled action in a CAD environment, and capturing the original via 3D scan to preserve for future modeling. I received another message not long after that the matching stock for the Nambu barreled action had been found. At this point, I had everything I needed to begin drawing the scale model to cross reference with my 2D drawings. Unfortunately, the matching internal components were never located, but we're still searching for a spare set that may still be floating around in private collections. 

Thus, the real work began. The thought from the beginning was always, "It really would be cool to be able to own a Nambu SMG someday", and that's exactly what we did. It may not be a 1:1 scale copy of the original, but it's about as close as you can get without introducing too many expensive, proprietary components. Starting with the rough overall shape of the original Nambu, over the course of 9 months or so, I designed a semiautomatic Pistol Caliber Carbine (PCC) that shares near-perfect similarity with the original Nambu, and it accepts commonly available surplus PPS-43 magazines, an AR-15 firing pin, and an AR-15 ejector to keep things simple and easy to replace. Since historically accurate metric diameter materials were unavailable, the next closest inch standard material was chosen to replace it. All in all, we got it as close as we could while still being able to locate the materials to produce it.

I drew a lot of inspiration for this design from the British Sten and Polish PPS-43 submachine guns in both form and function. I borrowed the extractor and fire control group design from the Sten, and the bolt from the PPS-43.  As the design progressed, we eliminated many of the proprietary parts we had designed in favor of commonly sourced components, such as the AR-15 firing pins and ejectors. Aside from it now being simpler to source those parts, going with non-proprietary wear components guarantees that the firearm can continue to be repaired for as long as they remain in circulation if and / when our company ever meets its untimely end or stops producing replacement parts.

Initially, the Tensei was a closed-bolt striker fired (linear hammer) design. The entire CAD model, including all subassembly components and other models, was done on my own over the course of a year in both 2D and 3D CAD software.

Halfway through the design process, we uprooted our lives in California and set sail for Rosenberg, Texas, with our sights set on greener pastures, and new beginnings. 

Initial Test Firing - October 2025

The initial test firing of the Tensei happened in October 2025, one month prior to accepting preorders. It was here that I started making the first significant changes to the design after testing revealed multiple problems with the linear hammer mechanism. 

While we were able to get a few succesful shots off, the linear hammer design had a range of issues including light primer strikes and the occasional slam fire. Some of these issues were determined to have been caused by the AR-15 firing pin we used that turned out to be far outside of standard spec, however some were caused or otherwise amplified by the linear hammer in several ways.

Luckily, by this point, I had already anticipated that there would be problems with the linear hammer, so instead I opted to change the design of the fire control group over to a true hammer fired design, using a linkage bar similar to several bullpup firearms.