There are some things to miss from the world before the iPhone: black rectangles get boring after a while. This is the 'talby', a phone designed by Marc Newson for au. It was shipped and sold (in volume) in 2003.
This chart, from JEITA, shows phone shipments from domestic Japanese manufacturers. The series are cellular and PHS, the Japan-only limited mobility system.
Part of this collapse is driven by migration away from domestic OEMs that were strong in featurephones to foreign smartphone makers, mainly Samsung and Apple. However, it seems to start too early for that to be the only explanation: there certainly weren't 20m iPhones and Androids sold in Japan in 2009. Other market dynamics at play (10 years ago I knew a lot about this market, but I haven't been paying close attention recently). Either way, the pain inflicted is pretty obvious.
A little window into how DoCoMo is still trying to drive technology and services when operators elsewhere in the world have long-since given up. This sort of thing is the reason why DoCoMo still refuses to range the iPhone. Also worth noting: DoCoMo has effectively replaced a core Google service on an Android phone with it's own service.