I was the person who designed the Pencil rocket. As my company didn't want to waste any personnel on such a profitless project, only I was appointed to work to the rocket. I calculated the thermal rating, which is a design fundamental, by myself. The calculator at that time was a hand rotating Tiger Calculator and it took manual labor to use it, unlike the electronic calculators people use nowadays. For example, if you wanted to calculate 2 x 5, you had to set the lever at 2 and rotate the handle 5 times, so the calculation was hard work. (Kakimi)
After defeat in WWII, aircraft materials were left over at Nakajima Aircraft Industries. When I went to the material storehouse, I mostly found pieces of Geralmine (Aluminum alloy), as well as steel materials, etc. Amongst them was a Geralmine round bar, approximately 30-mm in diameter. The name of this round bar was called "Chi-201". "Chi" was the standardized name at that time, which stands for Geralmine using the wartime standards of Nakajima Aircraft Industries. I told Professor Itokawa what I had found: "There were these materials called Chi-201 and I believe we could use them for the rocket." He replied to me, "Geralmine would melt from the heat of the rocket's combustion." But when I calculated the heat transfer, the temperature didn't appear to be that high. (Kakimi)
As I mentioned before, Toda had already taken over the propellants from Murata at NOF. These were the fuel used for bazookas during the Korean War. As bazookas needed quick ignition, several such macaroni-like fuels were used as cannonballs. Itokawa decided to use these as propellants.