If you are having trouble finding a diet shake, try Meal It.

I was looking for a simple protein shake and couldn't find anything other than a large size, so I went to Olive Young and saw that they were selling it, so I bought this Mill It.
It's a protein shake, but it's closer to a diet shake, so it was actually different from what I was originally looking for.
Still, the protein content is decent and there are a variety of flavors, so it seems like a good choice for those looking for a diet shake.
It's easy to eat one at a time, and the packaging is easy to drink, so it's very useful.
I mainly use it in the morning, but I think it would also be a good substitute for lunch or dinner.
For those of you who are concerned about diet management shakes, it might be a good idea to try the Meal It sold at Olive Young.