Otaku actually means, someone who doesn't have a social life and locks himself up all দিন and watches জীবন্ত অথবা plays videogames অথবা whatever আপনি like all দিন everyday.. xD
It's actually something bad. :p But most people use it as someone who loves জীবন্ত (^w^)
If আপনি think of it that way than both of them are otaku's :3
Personally, what I feel determines if আপনি are an otaku is if জীবন্ত is your passion and devotion. It shouldn't really matter how much জীবন্ত you've watched.
Although it's the loving of জীবন্ত that counts, I'd say that আপনি have to watch a decent amount of জীবন্ত to grasp the wide variety it has to offer.
I'd say it would take a bit less than 20, like 10-15 to get a feel of the জীবন্ত genres and choose which ones আপনি prefer.
Also, out of curiousity, was it this pic that made আপনি wonder about this? I've seen it before on Google.
posted বছরখানেক আগে
Free, Aikatsu, Pretty Cure, Fairy Tail, Lucky Star, Sword Art Online, Another, Kanamemo, Hidamari Sketch, School Rumble, Nichijou, Hetalia, Azumanga Daioh, K-on, Clannad, The Melancholy of Haruhi Suzumiya, Madoka Magica, The world God only knows, Squid Girl, and Ouran High School Host Club. I DID IT!