What are some Japanese expressions I can use?
Arigato - Thank you.
Domo - Thank you, not as polite as arigato. Domo and arigato can be combined ("domo arigato") and then become a more polite form of thank you.
Domo arigato gozaimasu - A very polite form of thank you, said while engaged in an activity. One can also say "domo sumimasen."
Domo arigato gozaimasta - Another very polite form of thank you, said after the meal or activity has concluded.
Dozo - "Please."
Hai - "Yes."
Konichiwa - Literally "this day" but colloquially meaning "hello" or "good day."
Oishii - "Yummy" or "Delicious."
Okonomi - Ordering sushi a few pieces at a time.
Omakase - Colloquially meaning "Chef's choice" and pronounced "oh-mah-kah-seh," this style of dining essentially offers the itamae the choice of what to serve you based on what he feels best represents his skills and what is available at that time..
Gochisou-sama deshita - "It was a feast!" (more commonly used)
Oishikatta desu - which means "it was delicious." (less commonly used)