Why is the title "Yotsuba&!"? The manga Yotsuba&amp;! is a story about a little girl named Yotsuba. So, the title using her name makes sense, but why is there an additional '&amp;' at the end?



This is the manga cover in English. It says Yotsuba&amp;! and sometimes it's written Yotsubato! on some sites.
Well, to (と) is a Japanese particle that functions like English "and". If, for example, you wanted to say "Yotsuba &amp; Tanaka", that would be Yotsuba-to Tanaka (よつばと田中). 

So I suppose it makes sense that one might choose to write Yotsuba-to! as "Yotsuba&amp;!".



As for why the title is "Yotsuba&amp;!" / Yotsubato in the first place - I suppose it's related to the fact that all the chapter titles are of the form "Yotsuba &amp; [something]", e.g. "Yotsuba &amp; the Elephant" (#19) and "Yotsuba &amp; Coffee" (#58).