Turn right into the long shopping covered arcade/mall strip across Atami Information Office near to station.
It is opposite end from the left side public dip foot hotsprings pool in front of station -usually surrounded by relaxed Japanese seniors sitting on benches taking off shoes dipping feet in hot steamy mineral water- a rare sight.
Ask any of the locals, and they will probably recommend the same sashimi/sushi restaurant. It is hard to miss and resist-- each time we entered, always filled with locals esp elders regular crowds at group tables floor culture at the rear (or tables/chairs at front).
Prices are highly reasonable for its sensational freshness.
The entrance is narrow as side in front of restaurant are two chillers loaded with seasonal fresh seafood pickled delicacies- advisable to pick a couple as they are really excellent.
We bought them and presented these gifts, and the Japanese senseis oohs and aahs at the labels and taste-served as one of the main course at NY.