This is Setagaya line of Tokyu Railways, the private company in Tokyo. It is categorized as a tram in Japanese law and has simple signaling, rail and car facilities as such.
It is just 2 cars but has frequent services, runs residential area slowly at 40 kmh maximum. Its length is 5 km and there are 10 stops. They are popular place to live because of good access using this line.
Currently Setagaya line is completely separated from roads, but historically it ran direct on congested road to Shibuya terminal which has been famous for busy crossing and shopping downtown.