To get to the Yurakucho Underground Shopping Street, take the escalator directly in front of the Central Exit of Yurakucho Station. You can then access Hibiya Station and Ginza Station.
Alternatively, you can go directly from the B1F of Yurakucho Itocia.
Near the Hibiya Station side of the underground shopping street, at the entrance to Yurakucho Marion, there is a three-way intersection leading to Yurakucho Station, Ginza Station, and Hibiya Station, and there are resting areas where you can sit nearby.
There are four single-seater stone benches.
The three-way intersection around the rest area is a wide space, which can be used when moving around Yurakucho Underground Shopping Street or as a meeting place in Yurakucho.
The stone benches seem to have been made by processing only the seating surface to be flat, so, of course, the seating surface is hard.
Also, the underground shopping street is not air-conditioned, so the environment may not be much different from outdoors in the summer or winter.
As for the congestion situation, I checked around 15:00 on a holiday and found that there was only one person using it, so it was not crowded.
In addition, as a meeting place within a 1-minute walk from Yurakucho Station in the same underground shopping street, "【Yurakucho Station】Central Exit Front Escalator Down Underground Shopping Street Resting Area with Seating" may be convenient to remember.
Why not use it as a meeting place or a resting place with seating around Yurakucho Station?