It's お宅, おたく or オタク. I won't get into why there are 3 different ways of writing it here, if you're interested in a detailed explanation of the Japanese writing systems, go to JapanesePod101.comm
How Do I Spell Otaku In Japanese Characters?
Otaku is a Japanese word that is used to refer to a person who is an obsessive fan of a particular theme, topic, or hobby. It is usually used to refer to fans of Anime and manga. You can see details about this word and how it is spelled in Japanese at the link below:
en.wikipedia.org
en.wikipedia.org