Tadaima !

ただいま !
Tadaima is, well, slightly harder than the previous ones, simply because it can be used at any time of the day - but I dont think its that hard!
Its translation to English is "I'm back!" or "I'm home!". There is a longer and more formal form, which is ただいまかえりました / Tadaima kaerimashita. I believe if we want to dissect the meaning for each word, tadaima means "just now", and kaerimashita means "came home" (past tense). So if you combine them, it will be "I just came home". But don't be confused, it is perfectly fine to say tadaima alone and people will assume that you are saying "I'm back".

Read more on my dA page ^^
Thank you!