This particular set was used probably less than a dozen times. Hardly used at all. To contrast this I'm posting a picture below showing my 20+ year old 8mm t-handle. I use the 8mm and 10mm the most by far. Once you break a bolt loose you can spin the t-handles very fast to remove it. They remove bolts very quickly.
Here are a couple links I have found explaining that Kowa Seiki being a Japanese company was hired by Honda to produce the tool kits for their motorcycles.