Connecting out of my neighborhood in Arakawa to the major transit hubs on the Yamanote Line, there are three simple methods by train:
-- Walk to Oku Station and take the Tokyo-Ueno Line to Ueno or Tokyo Station.
-- Walk to Oku Station and take the Utsunomiya Line to Akabane and the Saikyo Line to Shinjuku Station.
-- Take the Toden Arakawa Line to Otsuka-Ekimae Station and walk across to Otsuka Station on the Yamanote Line.
Machiya-Ekimae Station is also on the Arakawa Line, where you can connect to the Keisei Line (and get all the way out to Narita) and the Chiyoda Line. Riding the Toden Arakawa Line, it seems that most of the passengers are making local trips, or are riding it to take pictures of the last streetcar in Tokyo (sometimes it feel as if more than half of passengers are tourists), but it's actually a very good way to connect beyond the neighborhoods it runs through, once you know how to use it. Apart from the connections above, the Arakawa Line also makes it possible to connect to the Hibiya Line, Nippori-Toneri Liner, Namboku Line, Toei Mita Line, Yurakucho Line, Fukutoshin Line, and Tozai Line.
The area around Otsuka Station is not particularly noteworthy and on the walk south, I was mostly in a valley of anonymous early-'90s development. Again, noticing the various expat populations in Tokyo, there were a number of curry restaurants that, judging by English signage, seemed to be run by Pakistanis. I noticed signs posted outside them for the All Japan Quran Competition at the Masjid Otsuka-- first place prize: Umrah tickets! I walked back to Otsuka Station through back streets.
I have nothing in particular to report, but I will take a more careful stroll the next time I am in the neighborhood.