Thanks for your efforts on the Yawara site and the videos. It's great information and very well presented. Nice work! I hope that you continue to make more videos and keep the site active.
Good advice about use of a pen as a substitute Yawara stick when traveling. I have carried both pens and mini-Mag flashlights through airports on multiple continents without any issues. However, I always carry a generic pen and not the current fad "tactical" pens just to avoid any potential questions.
I got my first Kubotan in 1978, so my interest in the short stick goes back a while. Here's a little story regarding a connection between the pen and the Kubotan. In 1995, I attended a Kubotan certification program with Massad Ayoob at his Lethal Force Institute (LFI) in NH. As I recall Massad's presentation of the Kubotan's development, Takayuki Kubota was originally looking for a legal-to-carry item for self-defense use as an improvised weapon by his LA celebrity clientele. The techniques that Shihan Kubota developed for use as an improvised self-defense weapon were originally intended for use with a ball point pen, but he soon realized that the flaw with the pen was that it could potentially cause a penetration wound. The Kubotan was intended to be less dangerous than a pen would be in thrusting and stabbing attacks.
Interestingly, the "Kubotan" certification course at LFI in the mid-1990s was actually conducted using the "Persuader" version of the tool. The original Kubotans were produced by Monadnock in New Hampshire, but when Tak Kubota and Monadnock severed their relationship, Monadnock continued to produce the device but began the use of the name "Persuader". The "D‑Jammer” was another variation of the Kubotan that was developed by Massad Ayoob. It was designed to function as a tool for use in correcting firearm malfunctions, and is even threaded on the end to accept firearm cleaning tools. Lots of variations, but the martial applications are all the same.
I hope that you enjoy your travels, and I look forward to further videos.
All the best,