When you enter a restaurant with one or more people to eat a meal, it is proper etiquette to order at least one dish per person. If you want to try a number of different dishes, it is recommended that you share, and ask for individual small plates for that purpose.
A Japanese-style formal cuisine (kaiseki) restaurant will serve a set of dishes on individual trays that come out in courses. These course meals, which consist of many types of dishes, are designed for a single person, not to be shared with others. For this reason, be sure to order a course meal for each person seated.