Invisible Evidence

I have a Zippo lighter made in U.S.A. Although the outside cover is as it is, the inner unit had been replaced by the imitation which I got at a discount shop while I had been convinced that even a cheap imitation of 100 (1.2USD) could work almost as well as real one. Japanese "100 yen" discount shops sell the well-imitated no brand oil lighters, which is elaborate enough to cheat customers.
However, it shows that it is a cheap imitation when I try to ignite although its appearance looks like the inner unit of a real one. The imitation is incredibly hard to ignite. It gives off sparks. Nevertheless it won't ignite easily.
As soon as I gave it up and replaced the inner unit by a real one, it ignited easily by a single action.
The real one has a reason why it is called a real one although even if it is invisible.

from Tokyo