Citizen's analog/digital combination watch, "Crystron LC Chronograph Dual Time."
It is the originator of the model commonly called "DIGI-ANA".
Previously we introduced the model with white dial, but this time it's an even rarer model with a blue dial.
This "first generation DIGI-ANA" sold quite well at the time, and a fair number of them are being sold at online auctions, but I have rarely seen a model with a blue dial.
It is characterized by a white border around the display area.
When I found it at an online auction, I thought the black dial just looked blue due to the lighting, but when it arrived, it was a beautiful deep blue dial.
However, the model number and side number seem to be the same regardless of the color of the dial.
（41-9010、4-097416）

In this model, the digital watch is operated by buttons and the analog watch is operated by the crown, so they can be considered separate watches, but strangely, the daily difference between the digital and analog watches is almost the same, and when I take them out for the first time in a while, I find that the time is off by the same amount on both the digital and analog watches.
I don't know the details, but do digital and analog devices share the same quartz (crystal oscillator)?