Splitting bill in a kaitenzushi restaurant

We're travelling to Japan in a big group. Since everyone is likely to eat a different amount of plates with different value, it would be unfair to split the bill equally.

If we intend to pay for our own share, is it ok practice to ask the waiter to count only our own stack of plates and pay separately? How do we say this in Japanese?

Why not choose a place where all plates cost the same? If you then keep your own stack, you can do the math yourself.

We picked a kaitenzushi restaurant because it's near a fishing port and we want to try a variety of seafood. The only place I've been to where all plates are priced the same is very low quality, especially for items which are traditionally priced higher.

Actually, our intention to split the bill into 3 parts (not equal) and not individually for 8 people.

If we intend to pay for our own share, is it ok practice to ask the waiter to count only our own stack of plates and pay separately?

Yes. It is quite usual in your case.

How do we say this in Japanese?

Okaikei wa betsu betsu de onegaishimasu. Then the waiter will provide individual bills for each of you. Stack the same color plates together so that the waiter can count them easily.

You might better ask when you enter the restaurant.
Okaikei betsu betsu ni dekimasuka?

In 'Kaitenzushi',conveyor belt sushi bar, there are seats at the tables and bar.
You may seat at the bar and tell the maid to separate the bill before eating or seat at three tables.
Enjoy Sushi!

Actually, our intention to split the bill into 3 parts (not equal) and not individually for 8 people.

Then you should gather plates into three groups (and separate by colors of the plates) and say "give us three bills." If the waiter can't understand the phrase, he/she can understand what do you mean, I think.

Thank you for the responses and advice! We will try our best to make it less of a hassle for the staff as it is for us.

If the Kaitenzushi is popular one, then you may need to wait for a while. In that case the staff will ask you to write your name and the number of the persons, like Christina 3, John 2, Steve 3. If this is the case you don't need to say anything. At the same time though your group may need to seat separately.

"Separate bill please" is quite a common English expression among the Japanese.

"O-kaikei betsu de" is another simplified Japanese expression.

Then you can make circles with your arm to show different groups. For example, if person A and B can share a bill, and C and D another bill, then you draw a circle with your finger around A and B, and then another circle around C and D. "O-kaikei issho" means "same bill".

No problem.
You only stack the plates you finished simply into three groups(after different colors and patterns of plates, if you donft mind, because it helps the waiter to count correctly and swiftly), and when you pay, you ask the waiter to count separately pointing each group of the plates and saying gBetsu-betsu de onegai-shimasuh.

No muss, no fuss, just keep your own plates and pay your own bill!