What is the Tokyo Metro Festival like?

I'm visiting Japan in May and I noticed there is a rock festival on the last Saturday I'll be in Tokyo (May 23rd), and I'm trying to convince myself to attend it.

I found an available 1-day ticket and can have it shipped to my hotel. I'm just concerned about the train-ride home and the magnitude of the festival. I'll be going alone and I'm Caucasian.

What do you think?

Hello.
The Metrock festival in last year gathered more than 40 thousand people from all around the Japan for two days.
The nearest station from the event site is Shin-Kiba station.
The station has many train to the central of Tokyo till late midnight.
The finishing time of the event is 9pm.
I think you can go back hotel by train without any problem.

If you're talking about Metrock, these kind of festivals that start at noon and continues until the last business hours generally have people going in and out. So you can avoid the crowd at the station by leaving before Perfume finishes their last song.

But it's best to have an IC train ticket (such as Suica or Pasmo) or to purchase your return ticket as you arrive to Shinkiba station before the concert, so that you won't have queue for the ticket vending machine on your way back.

The website tells us that there will be free shuttle bus service between the station and the venue for those with tickets and wrist bands.
http://metrock.jp/access/
http://metrock.jp/artist/timetable.html

Thank you very much!

Have you heard from anyone if this event is pretty fun?

Also, I will have my JR Pass. I should be OK, yeah?

Thank you once again!