Why Japanese capacitors have been valued so much?
Are Japanese capacitors really better than others?
Generally speaking, Japanese capacitors do have outstanding quality. This is a widely agreed upon fact but the reason people tend to trust them over other capacitors has much more to do with marketing and stereotypes than it has to do with factual evidence of subpar performance of capacitors from other countries.
The materials and the temperature of the environment will affect a capacitor's performance quite a bit. Japanese manufacturers know this and have taken great care to advertise how much time and effort is put into considering these two factors during the design stage.
Secondly, Japanese manufacturers market their production processes as overly cautious and pristinely clean in order to show how carefully constructed their capacitors are. People tend to connect this show with reliability allowing Japanese manufacturers to project a strong impression on the rest of the world that all Japanese products are of a higher quality than products from other regions and countries.
Last but not least, the Japanese government is directly and publicly involved in funding new energy industries and research for passive components development which lend an air of legitimacy and prestige to all Japanese technology/component manufacturers. This is why Japan has even been called the domain of the capacitor market by some.