Vintage SEIKO "Time Sonar" 7015A-6010S, ca. 1978 (from Tim)

The dial inscriptions are ...
SEIKO TIME SONAR AUTOMATIC
on the left side, then the little lightning-like icon (for DAINI-SEIKOSHA) and START STOP and SET TO ZERO on the right. And of course at the bottom at 6 o'clock, the most important inscription: JAPAN 7015A - 6010S