After witnessing a very long and confusing conversation between, apparently, an house elf, and his friend, Dobby bowed with a greatful squeak and with a crack, vanished.
"There you have it!" She hummed with a mischievous smirk, "Now, ready to crash a party?"
Three minutes later Mayumi is happily chatting with Mr Mason about their mutual interest in Japanese culture while the Dursley's watched on with strained smiles, Harry found himself sitting in the corner, feeling quite very awkward.