People who are sentimentalists have strong feelings and emotions about things, especially about the past.
Being sentimentalists can be seen as a good thing because it means they care a lot about things, but sometimes it can be seen as a bad thing because it means they might not be practical.
Examples:
The sentimentalists cried when they saw the old photo.
My grandma is a sentimentalists because she keeps all the old letters.
The sentimentalists in the movie always remember the past.
The sentimentalists wanted to keep the broken toy because it was special to them.
The sentimentalists never throw anything away, even if it's broken.
The sentimentalists always talk about the good old days.