Direct from Narita to Okubo Station

Can Narita Express reach Okubo Station directly? If not, any advice on the correct route to take.

No, but you can take the NEX to Shinjuku and transfer to the Chuo Line one stop to Okubo. The route is fully covered by the Tokyo Direct Round Trip Package amongt others.

http://www.japan-guide.com/e/e2359_nex.html

Thanks for the info. However, based on the link you have enclosed, the Okubo Station is not covered in the package deal. The name of the stations under the deal are listed in the diagram. Do advise if my understanding is correct

It can't possibly list ALL stations valid on the ticket because it would fill many, many, many pages.... Okubo is allowed.

It would not be possible to list all stations on the diagram, as there are too many. Okubo station is located on the Chuo-Sobu line, which links Chiba and Mitaka stations going through Akihabara and Shinjuku. This line is entirely covered.

https://en.wikipedia.org/wiki/Ch%C5%AB%C5%8D-S%C5%8Dbu_Line
http://www.jreast.co.jp/e/pass/nex_round.html#category05

In this and the next messages which I post here, I omit any macron which indicates a long vowel.
"Chuo Line" is pronounced like chew-all-line.

[Route to Okubo Station or Shin-Okubo Station in Shinjuku City]

In this section I make explanations on the supposition that you will head to a place near Okubo Station in Shinjuku City in Tokyo Metropolis.
(There are several stations whose names end with "Okubo" in Kanto Region; if your destination is far from this Okubo Station, please explain it more in detail.)

Narita Express trains run not via Okubo Station or Shin-Okubo Station.
You can change trains in Shinjuku Station.
- Shinjuku Station of JR:
https://www.jreast.co.jp/e/stations/e866.html

Narita Express trains destined to Shinjuku, Ikebukuro, Omiya or Takao arrive to Shinjuku Station at Track 5 or 6.
After disembarking from your Narita Express train at Track 5 or 6,
you can go up by elevator or staircase to the pathway,
see Southern Terrace Gate on your right,
walk straight to the west end of the pathway,
go down to the platform for Tracks 15 and 16
and catch a Local train on Chuo Line at Track 16;
the next stop will be Okubo Station.

All rapid trains on Chuo Line skip Okubo Station; they use other tracks in Shinjuku Station, so you are not likely to catch one mistakenly.

If Shin-Okubo Station happens to be closer to your destination, alternatively you can switch to a train on Yamanote Line's outer loop in Shinjuku Station, which departs at Track 15; the next stop will be Shin-Okubo Station.

[Tips on transportation from NRT]

Many Narita Express trains leaving NRT are initially destined to two stations; each of such trains gets divided in Tokyo Station into two trains including one running for Shinjuku.

Narita Express trains leaving NRT which are initially destined to only Ofuna or Yokohama run not via Shinjuku Station.
Currently there are four such N'EX trains, which leave NRT in the afternoon roughly from 12:45 to 19:20.
If the earliest N'EX train which you can catch is one of these four trains,
you can take this N'EX train to Shinagawa Station and switch there to a train on Yamanote Line's outer loop for Shinjuku
or, simply wait for the next N'EX train which is to bring you to Shinjuku Station.

You can try to reserve your seats in JR Limited Express (including Narita Express) and Shinkansen trains at a counter in JR East Travel Service Center.
When the service center in your JR station in NRT is closed, you can visit a nearby JR ticket office for that purpose.
- JR East Travel Service Centers in NRT:
https://www.jreast.co.jp/e/customer_support/service_center.html

Currently two railroad operators, JR-East and Keisei Electric Railway, have
Narita Airport Stations in NRT Terminal 1
and (Narita) Airport Terminal 2 Stations in NRT Terminal 2,
but in NRT Terminal 3 there is no railroad station.
Some buses leaving NRT for Tokyo start from NRT Terminal 3.
- Traveling between NRT Terminals 2 and 3:
http://www.narita-airport.jp/t3/en/access/terminal/index.html

[N'EX TOKYO Round Trip Ticket]

Unless you get outside a ticket gate on the way, you can travel with a ticket in this package from a JR station in NRT through to either Okubo or Shin-Okubo Station.
The same applies to your traveling back from a station in the designated area.

While the word ticket is in a singular form in the tittle, actually two one-way tickets are in this package.
It can be a good deal if you make the roundtrip within 14 calendar days.

The name of the stations under the deal are listed in the diagram.

That diagram is a map to show the designated area where a ticket in this package can be valid.
(The japan-guide explanation goes "any JR station in the area shown on the map"; you seem to have mistaken it for any JR station among the stations shown on the map.)

Even JR-East itself indicates only some major stations on the map of the designated area of validity.
- N'EX TOKYO Round Trip Ticket:
http://www.jreast.co.jp/e/pass/nex_round.html
Around the center of this map you see the JR section Shinjuku -- Mitaka, which is a part of Chuo Line.
On this map only Kichijoji Station is indicated in the middle, but actually seven other JR stations exist there including Okubo Station, which is next to Shinjuku Station.

[Routes for JR-East trains]

There are through Local trains which run on Chiba or Tsudanuma -- Kinshicho -- Akihabara -- Ochanomizu of Sobu Line and Ochanomizu -- Shinjuku -- Nakano or Mitaka of Chuo Line.
The whole route Chiba -- Ochanomizu -- Mitaka for Local trains is often called Chuo-Sobu Line.

Faster trains such as Narita Express trains and Sobu Rapid trains take a route which is parallel on Chiba -- Kinshicho to Chuo-Sobu Line, but it goes not by Kinshicho -- Akihabara -- Ochanomizu but by Kinshicho -- Tokyo.
(Most Narita Express trains skip Chiba Station and all Narita Express trains skip Kinshicho Station.)

Usually JR-East indicates on its network maps
the route often called Chuo-Sobu Line for Local trains in a yellow color,
the route between Chiba and Tokyo for faster trains in a cobalt-blue color
and Yamanote loop Line in a yellow-green color

Thank you everyone for the valuable info and your precious time to reply my queries.