You are right. Jujutsu is also spelled as jujitsu, ju-jitsu, jiu-jutsu or jiu-jitsu.
The pun was nice - unusual both as the answer and as a comment on the rarity of the response. But, there are a few words available. We also have cumulus, tumulus and fumulus.
There is even a word of 7 letters with 4 Us - muumuus which are long loose fitting dresses made of lightweight fabric printed with bright, stylized Hawaiian themes (such as flowers and palm branches) (singular is MUUMUU).