I used to live in Tokyo for the past 2 years, and more precisely, I had just around the corner the Square Enix HQ, and besides the building, there is the Square Enix fans sanctuary, Artnia.
To get there, the most comfortable option is to drop off at Higashi Shinjuku station, with both Fukutoshin line or Oedo Line. Artnia and Square Enix are right next to the station. The other way is to walk from Shinjuku station, a 2km walk. Good option for urbanites to admire the streets of Shinjuku.
You can visit their website for information and access as well. Artnia
Shop inside, plenty of merchandise from the main video games, Dragon Quest and Final Fantasy sagas.
Most of the drinks in the menu have names from the videogames series, like potion, chocobo feather and so on..
This is one of my favourite places in Tokyo, as a Square Enix fan, listening to my favourite games soundtrack while enjoying a hot coffee, surrounded by all that merchandise and game art is something you can’t do everyday. As a fan, is paradise.