I purchased a dell laptop from Japanese Dell website. I wanted the English OS as I am non Japanese, but it wasn't possible (I thought what kind of customer care it is?) I don't mind the Japanese keyboard though!

Then I installed English language pack and now the interface language is English. But still Japanese characters are appearing here and there. Eg, on the welcome screen, on the wi-fi connecting menu so on. 

How can I get rid of this?

Thanks in advance!