Picked up a 1999 NTT DoCoMo Browser Board yesterday, at my usual place I go to find electronics near my house.
It really isn't that useful anymore but back in the days, it was a pretty neat device that you could connect to the internet via a cellphone or PHS.
I found a English technical journal about it from NTT DoCoMo so I will list the link here:
https://www.nttdocomo.co.jp/english/binary/pdf/corporate/technology/rd/technical_journal/bn/vol1_2/vol1_2_014en.pdf