Parking can sometimes be a trick on the waterfront in Portland.
During the day:
The only off-street parking spaces available during the day are six free parking spaces reserved for Sapporo customers in the public parking lot adjacent to the patio seating area immediately to the east (right side, toward the ferry terminal) of the restaurant. See the picture above.
Enter that lot through its main entrance to the left of the restaurant.
During the Evening and Weekends:
In addition to the six spaces available during the day, customers of Sapporo Restaurant may park in the parking lot located directly behind the restaurant.
Enter that lot from the street to the right-hand side of the restaurant, at the stop light.
Drive around the back and park in any of the spaces that would be normally be occupied during the day by employees of various businesses located nearby. See the picture above (the back of Sapporo Restaurant is at the left of the picture).