it sounds like I cannot get this direct travel since I'm arriving after 5 p.m. On Saturdays / Sundays / holidays, no direct train is available for Asakusa after 17:00 in NRT.
Public holidays in Japan in the coming 6 months will be April 29, May 3 - 6, July 21, September 15, September 21 and October 13.
On weekdays, two trains are scheduled to run after 17:00 from Narita Airport for Asakusa by Keisei Main Line, Keisei Oshiage Line and Toei subway Asakusa line.
: Narita Airport (18:02) -- Airport Terminal 2 (18:05) -- (19:19) Asakusa.
: Narita Airport (18:54) -- Airport Terminal 2 (18:56) -- (20:05) Asakusa.
In order to take a train on Keisei Main Line, you need to pass through both entrance and intermediate gates in your Keisei station in NRT.
Anyway, I recommend you would pack lightly.
You may encounter staircases on the way, and in order to avoid them you may need to take a roundabout route.
staying at The Gate Hotel Kaminarimon There is a supermarket in the same building, which can be a landmark for you, on the ground floor (= 1st floor) at the corner facing east-west Kaminarimon-dori.
http://www.ozeki-net.co.jp/shop/tokyo/taitou/asakusa/index2.html- Map of Asakusa Stations of Toei subway and Tokyo Metro
http://www.tokyometro.jp/station/asakusa/yardmap/images/yardmap.gif- Tokyo Subway Route Map
http://www.tokyometro.jp/en/subwaymap/pdf/routemap_en.pdf[From Asakusa Station of Toei subway]
Exit A4 and A5 are closest to the hotel, but as you see on the station map, they are far from Toei subway Track 1 platform, and the pathway includes several staircases.
Alternatively you can reach Exit A2b using two elevators (unless none of them happens to be suspended) and walk for about 300 meters, though itfs a little roundabout.
-- (Elevator up) -- Exit A2b
-- (crossing Edo-dori northward, turning right)
-- (crossing Asakusa-dori eastward, turning left)
-- Asakusa-dori -- the 1st corner -- (turning right)
-- (proceeding northward for about 250 meters to Kaminarimon-dori)
-- the corner of the supermarket -- (turning left)
-- (proceeding a little) -- The Gate Hotel Asakusa Kaminarimon.
[From Asakusa Station of Tokyo Metro]
If your Tokyo Metro train arrives to Track 2, you can reach Exit 1 on the route shown in a red line on the station map.
If your Tokyo Metro train arrives to Track 1, you need to use staircases in order to reach Exit 1.
[Other railroad routes]
You may hope to have a reserved seat on some of your way to Asakusa. In that case, you have some options.
For backpackers, Route (a) is recommendable.
I mention Route (b) for travelers who hope to avoid staircases, even short ones.
(a) Taking a Keisei Skyliner to (Keisei) Ueno, then walking to Ueno (G-16) of Tokyo Metro, then taking a local train on Ginza Line to (G-19) Asakusa.
: This route sounds fastest, requiring about 1 hour.
: Probably the pathway to Ueno (G-16) includes a staircase.
: With regular tickets, the one-way cost is 2640 yen per adult.
: If you plan to make several trips on Tokyo Metro lines (not including Toei subway Asakusa / Oedo / Shinjuku / Mita line) in one or two consecutive days, a Keisei Skyliner & Metro Pass is worth considering.
http://www.tokyometro.jp/en/ticket/value/airport_bus/index.html(b) Taking a Narita Express of JR-East to Tokyo, then taking a Local train (bound for Kurihama or Zushi, using the same platform) to the next Shimbashi, then walking to Shimbashi (A-10) of Toei subway, then taking a local train on Asakusa Line to (A-18) Asakusa.
: This route requires about 1 and a half hour.
: The transfer pathway to Shimbashi (A-10) is equipped with escalators.
: With a NfEX Tokyo Direct Ticket which can be valid to Shimbashi, the one-way cost is 1710 yen per adult.
https://www.jreast.co.jp/e/pass/nex_oneway.html- Map of Shimbashi Stations of Toei subway and Tokyo Metro
http://www.kotsu.metro.tokyo.jp/subway/stations/shimbashi/i/solid.gif
