I have a layover from 8pm to 8am at narita

Ive never been to japan, Im going to be there over night so id like to get a game plan. Im down with doing anything from visiting temples to seeing cosplayers to eating and partying. I would prefer to keep a low budget maybe around 150000 yen. I imagine I cant sight see too much given my time frame but Id just like to get out there.

Any tips would be much appreciated

A low budget of 150000 yen? $1320??

Unless you want to eat at a 3 star Michelin restaurant and stay at a 5 star hotel, I guess...

Most stuff will be closed when you arrive (temples and parks), probably no cosplayers about (if you wanna see them, best chance is on a Sunday) and open maybe around 9-10 am.

Allow roughly an hour from the airport to Tokyo "downtown" and back, if not more.

How about going to Shinjuku, Shibuya or Ginza for couple hours, just to see night Tokyo, then to Monogatari onsen in Odaiba (it's public bath), open overnight, you can experience japanese bathing and relax there. They have food and relaxing rooms in addition to bathing facilities. Website
http://www.ooedoonsen.jp/daiba/english/

If you would like to see temples...

A good option could be going to Asakusa and check out sensoji temple and grounds... even though the shops, and mostly everything will be closed you can check out amazing temple buildings and one of the most incredible parts of tokyo

Which date?
How many nights?

I put one too many zeros in my budget lol. I will be there the night of dec 12 into the morning of the 13th

I'm just gonna throw this out here. If you're a fan of ramen, there's a chain of shops called Ichiran that has locations all over Tokyo with some open all night.
Some people criticize it cause it's a chain but it's my favorite place to get ramen. I've never been anywhere that I like as much.
Also it really suits the solo traveler, you order from a vending machine, sit in this little cubicle thing, you press a button to call your waiter and your food is delivered through a little hole with a curtain (you don't even see your waiters face). You don't have to deal with anyone and you can focus on your ramen.
Great place. If I had only 12 hours in Tokyo they'd definitely be on my list.

If your departing flight is at 8am you'll either have to stay at a Narita area hotel or catch one of the first trains out of Tokyo very early in the morning. For the 1st option, the last train from Tokyo to Narita (city) is around 1130.