The NHK-world Japan on demand is now broadcasting the TV programme "DESIGN TALKS plus : Signage Design" which was taken on September 6, 2018. Originally it was made in English and translated in Chinese soon later, then planned to broadcast until March 31, 2020 but it will be extended until March 31, 2022 because it has a good reputation.
Actually Keiichi Koyama is not a main character in this programme but he is talking about graphical symbols in the middle of this film, 14 minutes from start. So we would be happy if you could watch it.
for Chinese;
https://www3.nhk.or.jp/nhkworld/zh/ondemand/video/2046076/
for English;
https://www3.nhk.or.jp/nhkworld/en/ondemand/video/2046076/
