WTF is this? Part 1 (an ongoing series/competition)

Walking around Tokyo you see some strange and wild stuff. I thought I fun way to share that experience with you all would be to post pictures of some of that stuff, and see if anyone can guess what it is/does/contains etc.

I'd like to make it kind of a competition, whoever's guess is the closest (or funniest, most creative, etc.) will win the prize. The exact nature of this prize has yet to be determined, but I promise you, if you win you will get a prize and it will be sweet.

So anyway here is the first entry into the series, found right outside Shinjuku station, the busiest train station in the world (more on that to come later).

What do you think goes on in this building?