The WiFi is not only weak but spotty. My connection got lost sometimes. The coffee is great though. It has wide variety of single origin coffee. [Update] The ground floor seems to have better WiFi connection.

A few power sockets upstairs on the floor

Yes, as others noted, the WiFi of the verve themselves can be slow, like 10Mbps down max. However, there is another WiFi called Tokyo Free Wi-Fi, which is the metro government WiFi and you can register and download profile from https://wi-fi.metro.tokyo.lg.jp That one reaches close to 70Mbps down on the second floor of the Cafe. Worth checking them out. And yes, the coffee tastes good.