Taxis from Haneda Airport to Shinjuku

Hello,
We are a group of 4 people who arrived at Haneda Airport at 00:00 hours.

We need catch axi to arrive at the hotel in Shijuku zone.

How much money does it cost? And how many people fit in a taxi (considering the luggage)

Thanks

The fare is 8000 yen plus a few hundred yen in expressway fees. The most common taxis seat 4 passengers. Larger sized ones that seat 5 passengers can also be found:
http://www.japan-guide.com/e/e2021.html

Thanks for the reply.

Taxis have to book them? Or not necessary?

No need to book ahead of time. Also, 4 might be tight for one taxi if you have large luggage or more than 1 piece per person.