Comiket Nostalgie

Comic Market - or Comiket, as this event is usually called - is the world’s biggest dojinshi (fanzine) fair and arguably Japan’s largest otaku gathering, visited by more than half a million people twice a year.

Here's a great video about the 28th edition (1985) where you can see how cosplayers looked back in the day.

You can find more information on dojinshi, Comiket, and other such events in the Odaiba chapter (p. 116-124) of the brand-new Tokyo Geek's Guide.
https://www.amazon.com/Tokyo-Geeks-Guide-Cosplay-Ultimate/dp/4805313854/ref=zg_bsnr_16797_4?_encoding=UTF8&psc=1&refRID=2REEK0JNGHT4XMZY98K4