Desu

This character overuses or overemphasizes the word ~desu at the end of their sentences.

Desu is a Japanese copula often given the translation of 'to be' or 'it is'.
https://en.wikipedia.org/wiki/Copula_(linguistics)#Japanese

Note: -ssu used to be an alias of this trait instead of a separate trait. If you see a character tagged with this thread instead of -ssu when the latter would be more appropriate, please edit the character page accordingly.