Saxophones Yaganisawa Alto 900 with strange serial number

[profbert]

Hi, I bought a nice, great playing and good looking Yaganisawa alto. The instrument though has an unusual serialnumber: Japan 900 , 901 82 141. Does somebody know something about year of production and/or other information of this saxophone?
Thanks!
Bert

 

[Tenor Viol]

I have a B900 bari, and I think 900 model series dates to around 1990.