5 hours layover in Tokyo - what to do?

Hi i'm arriving in Narita Airport by Singapore Airlines at 7.40AM and my next flight with Jetstar leaves at 12.40PM.

Q0- are these 2 airlines in the same terminals?
Q1- do I have to go through immigrations and collect my bags?
Q2- is there lockers in the terminals where Jetstar is?
Q3- 4hours layover is there anywhere outside the airport i can go to? any tourist bus/hop on hop off bus?

thank you
JS

are these 2 airlines in the same terminals?

No. Singapore Airlines uses T1, while Jetstar uses T2.

do I have to go through immigrations and collect my bags?

Yes, you will have to go through immigration. Not sure whether the luggage can be forwarded directly or not, though.

is there lockers in the terminals where Jetstar is?

Yes:
http://www.narita-airport.jp/en/guide/service/list/svc_07.html

4hours layover is there anywhere outside the airport i can go to? any tourist bus/hop on hop off bus?

Some options are introduced here:
http://www.japan-guide.com/e/e6400.html

thank you Uji
I remember seeing somewhere there is a bus that i can catch from Narita Airport (?? maybe or Narita Station) that goes to the Nartiasan temple? fare is 200yen i recall.
Do you know if it's still functioning?

No, I think that is the one which was discontinued, as mentioned here:
http://www.japan-guide.com/e/e6402.html

The easiest way to travel between the temple and the airport besides a taxi is to take the train from nearby Keisei or JR Narita Station. Walking along the Omotesando approach is part of the fun, anyway.

Check with your airline if they have an interline agreement with Jetstar. If so you can transfer airside between T1 and T2 after going through security check at flight connections.

If you want to leave the airport you need to go through immigration and customs. If your airline doesn't have an interline agreement, you'll need to pick up your bag here and re-check in the other terminal. You can leave your hand luggage in lockers or use left luggage service for a fee.

Note that although immigration will be quick at this time, if you have to take your luggage to T2 and re-check it will add time. Coupled with having to arrive early for your next flight to clear security, there won't be that much spare time, but you could probably manage 1-2 hours in Narita City depending on how long you have to wait for transport.

What I said above only applies to international flights on Jetstar.

If you are taking a Japan domestic flight on Jetstar, then you have to clear immigration in T1 and collect your luggage in T1 before clearing customs. Then recheck your bags in T2. Although, check in may not be available 5 hours before your flight. You will have more time outside the airport though, as the domestic flights allow a shorter time to clear security and get to your gate.

Yes, I assumed that the Jetstar flight is a domestic one.

yes jetstar is a domestic flight. so I guess I arrived T1 have to clear immigration and go check in at T2 again.
if there is not enough time to get to naritasan I'mnot sure howto kill time in the airport.

that's really disappointing the retro bus has been discontinued... I was hoping to catch that to NaritaSan temple

It's easier to visit the temple by train, anyways! The train is faster and much more frequent. Keisei limited express trains leave every 20 minutes. They take just 10 minutes, 250 yen to reach Keisei-Narita Station from where you can follow the interesting Omotesando to the temple:
http://www.japan-guide.com/e/e6401.html

The loop bus used to be very infrequent and probably slower. That is probably one of the reasons why it got discontinued.

thank you very much for your help Uji!

I found this really helpful video about just that!

How to make the most of a couple of hours in Narita! There is actually soo much to see and do!

http://www.youtube.com/watch?v=326PIthEg_Y&feature=gp-n-y&google_comme...