Oh? That weird underpass? Yeah, so there’s a way to see it in Google Maps / streetview - look for the Toei Metro Asakusa line Sengakuji station 都営浅草線 泉岳寺駅. The subway line is partially built under National Route 15. If you look at the area where exit A3/A4 is located, you should see the Takanawa Okido gate memorial. Look at the southern edge of the gate memorial you should see an alley of sorts leading east towards the tracks for the multiple train lines in the area (Yamanote, Keihin-Tohoku, Tokaido Main line, the Tokaido Shinkansen, the Yokosuka line, etc)..It’s opposite Takanawa 2-Chome 17. You should be able to use streetview to look at the corner where the underpass begins, and there are photo spheres posted by pedestrians inside the underpass covering the entire walkway.
The entire area used to be a train storage yard (JR East Tamachi dispatch facility) until it was decommissioned when the Oimachi facility further south was expanded. It’s also near a waste treatment/drainage facility for the Shibaura waterfront. The entire area east from the railways were built-up/reclaimed from the shoreline and caused tons of headaches for JNR when they tunneled the Yokosuka line underneath the area back in the 1970s in an attempt to reduce congestion on the train lines between Kanagawa and the capital.
The underpass was a vestige of back when Tamachi/Shibaura was a lot more industrial and salarymen heading towards area firms coming off the Asakusa line stop had to go to work without looping to avoid the train yard. Both Toshiba and Honda were based near the Shibaura waterfront, and Sony used to do R&D there.
Tamachi/Shibaura is a lot more boughie nowadays as many of those old warehouses and offices were replaced by luxury condos and whatnot, but there are still corporate firms based there, like Tokyo gas, Toshiba, FamilyMart and Bandai Namco’s video games division.
The entire train yard area will be replaced by an elevated podium retail/office/residental complex called Takanawa Gateway City, anchored by a new Yamanote line backfill station (opened in time for the Tokyo Olympics) and the vehicular route connecting the area around Sengakuji and Shibaura is not expected to be re-opened until 2032 when the construction on top is finished (that’s going to be replaced by a bridge taking you up to the new podium level). The replacement pedestrian/cyclist tunnel (opened 2023) is actually reusing a drainage channel that was nearby. Construction is also happening up north at Hammamatsucho (Tokyo World Trade Center/Monorail terminus reconstruction), Tamachi/Mita (they just finished the msb complex) and south at Shinagawa (Keikyu is elevating their terminus and getting rid of that infamous railway crossing over Yatsuyama-dori, JR East themselves are working on a tunnel to Haneda Airport), and I think Tokyo Metro is working on a Tozai line extension as well.