Answer:
"kicks off".
Step-by-step explanation:
A casual tone is the use of any language that is informal or the language we use while talking to a friend. It may include the use of certain language or phrases, words, or grammar that is informal.
In the given paragraph, the casual tone is or can be detected by the use of the word "kicks off" which makes the whole sentence or message an informal one. It suggests a casual tone, an easy-going approach, and is not formal.