Otaku
Otaku is a Japanese slang word, deriving from the honorific "お宅" (otaku), meaning "your house", that has come to mean someone who obsessively exerts time, money, and energy into a hobby. Otaku have a deep, complex knowledge around a particular subject or area of study, and is oftentimes (esp. in the West) used to refer to avid consumers of anime and manga. The term can also be compared with Hikikomori.