When I was in elementary school, there was a vacant lot behind our house where I built a secret base with my neighborhood friends.

We dug a hole with a shovel, covered it with a plastic sheet, and used dried branches to prop it up from the inside. This half-underground structure, like a makeshift bunker covered with cloth, was very cozy and offered great visibility for spotting “enemies.” I was so proud of it that I immediately showed it off to my family, who were supposed to be the “enemies.” So, it wasn’t much of a secret base after all.

The development theme this time was how to merge the sense of a secret base with the functionality to lighten human-powered travel. The goal was not just comfort but also lightweight, compact, and easy-to-use designs. This is also the common concept of the NINJA series.

The first attempt was to add triangular cloths to both sides of the NINJA TARP. This tarp is very easy to set up, so the aim was to achieve the same ease of setup. The first test was at the OMM race in Nagano in 2016, where condensation caused tension loss. We discovered that using the same nylon fabric as the tarp led to uneven tension on the shelter due to humidity changes. While not an issue for tarps or dome tents, it was a problem for floorless shelters. Switching to polyester fabric later solved this issue.

The more challenging part was the height adjustment mechanism. For solo hikes or bikepacking, a lower ceiling is better, but for styles using cots or chairs, a higher ceiling is preferable. Could we make it easy to adjust the height using just the poles and guy lines without compromising the styling?

After testing with CAD, scale models, and full-sized prototypes, we arrived at a simple structure: designing the body with a low ceiling height and adding skirts to the bottom. This allowed not only height adjustments but also easy temperature control and ventilation. With practice, adjustments could be made from inside the tent. The skirts proved highly effective across various seasons and scenarios. Additionally, it paired perfectly with the NINJA NEST. At 1150g, it was suitable for most adventures.

Thus, the NINJA SHELTER was born. Its interior space felt just like the secret base from my childhood. The simplicity of fabric and poles, combined with a comfortable level of darkness, created a calming and liberating environment. This tent brings that same feeling of relaxation and freedom.

Use it as a base camp for outdoor activities, for 2-3 person camping parties, or for stealth camping in the forest—but always let your family know where you’re going. After all, both gear and secrets are best when they’re light!

Pack and go!