I was always fascinated by anime, manga, light novel and such, but the reason for starting to learn Japanese, was the lack of translation of some novel, I was interested in.
For example the visual novel called: Mahōtsukai no Yoru (a type-moon VN) and the light novel Yuusha, Aruiwa Bakemono to Yobareta Shoujo (from the author of The Girl Who Ate a Death God , The Girl Who Bore the Flame Ring and such).
It might sound silly, but when somebody wrote on a bulletin board, that he is going to learn Japanese faster than the translation progresses, to which many of the users positively replied to,
I mindlessly thought (it happens)- I can do that too!
I initially wanted a second foreign language to my humble English and ended up trying Italian, french and Russian, which all kind of are boring, I guess. At the end Japanese provided enough “peculiarness” that my interest did not cease and it added value because of my hobbies.
In addition to that I already bought some quite advanced light novel in Japanese, I look forward to read to, so there is literally no escape ;D