TReportedly, the Japanese secondhand market is reportedly flourishing. Reportedly, the Japanese secondhand market is flourishing.

or "It has been reported that the Japanese secondhand market is flourishing."

The Japanese secondhand goods market is reportedly flourishing in Japan. The secondhand goods market is reportedly flourishing in Japan.

I clarified the meaning a bit.

Its growth is driven both by strong overseas demand for Japanese goods, and by the fact that consumers in Japan todaymodern Japanese consumers have little hesitation about buying items from the resale market. Its growth is driven both by strong overseas demand for Japanese goods, and by the fact that modern Japanese consumers have little hesitation about buying items from the resale market.

Minor fixes for readability. Some advice for commas that we are taught in school: if you read your sentences aloud, add a comma wherever you pause for breath :-)

In English, reuse is generally used in an environmentally conscious context, meaning to use something again rather than to discard it. In English, reuse is generally used in an environmentally conscious context, meaning to use something again rather than to discard it.

Your sentence is perfectly correct, I will just suggest adding "to" as an alternative suggestion - personally it sounds a bit more natural to my ears but is somewhat subjective.

In English, "reuse" is generally used in an environmentally -conscious context, meaning to "use something again rather than discard it". In English, "reuse" is generally used in an environmentally-conscious context, meaning to "use something again rather than discard it".

Added quotation marks, it makes meaning clearer when discussing word definitions. You can also use single quotes (' ').

Japanese media haves begun adopting this pseudo‑English term because secondhand is perceived as sounding cheap or outdated, whereas reuse carries a more neutral—and supposedly cooler—image. Japanese media has begun adopting this pseudo‑English term because secondhand is perceived as sounding cheap or outdated, whereas reuse carries a more neutral—and supposedly cooler—image.

Japanese media haves begun adopting this pseudo‑English term because secondhand is perceived as sounding cheap or outdated, whereas reuse carries a more neutral—and supposedly cooler—image. Japanese media has begun adopting this pseudo‑English term because secondhand is perceived as sounding cheap or outdated, whereas reuse carries a more neutral—and supposedly cooler—image.

or you can say "Japanese media outlets have begun..."

Japanese media haves begun adopting this pseudo‑English term because "secondhand" is perceived as sounding cheap or outdated, whereas "reuse" carries a more neutral—and supposedly cooler—image. Japanese media has begun adopting this pseudo‑English term because "secondhand" is perceived as sounding cheap or outdated, whereas "reuse" carries a more neutral—and supposedly cooler—image.

In reality, the Japanese term “reuse” is a marketing invention invented by "the industry experts" who were unaware of how the word is actually used in English. In reality, the Japanese term “reuse” is a marketing invention invented by "the industry experts" who were unaware of how the word is actually used in English.

In reality, the Japanese term “reuse” is a marketing invention invencreated by "(the) industry experts" who were unaware of how the word is actually used in English. In reality, the Japanese term “reuse” is a marketing invention created by "(the) industry experts" who were unaware of how the word is actually used in English.

"created" fits better than "invented" since it reduces redundancy, but "invented" is not wrong.

In reality, the Japanese term “reuse” is a marketing inventionterm invented by "the industry experts" who were unaware of how the word is actually used in English. In reality, the Japanese term “reuse” is a marketing term invented by "the industry experts" who were unaware of how the word is actually used in English.

In reality, the Japanese term “reuse” is a marketing invention inventbuzzword coined by "the industry experts" who were unaware of how the word is actually used in English. In reality, the Japanese term “reuse” is a marketing buzzword coined by "industry experts" who were unaware of how the word is actually used in English.

Buzzword: a trendy word/phrase. To coin: to invent a word or phrase.

Experts in Japan often refer to this sector as the “reuse market,” but I think this usage is essentially Japanese English. Experts in Japan often refer to this sector as the “reuse market,” but I think this usage is essentially Japanglish.

"Japanglish" is a colloquial term which will be more readily understood by native speakers. Combining the language names like this (other examples: Spanglish, Franglish) indicates that it's incorrect English in the particular style of that ethnicity.