Nightlife solo traveller

Hi!

I'm a Belgian guy, late 20ies, now staying in Shinjuku for two weeks.
I'd like to go out drinking, explore the nightlife a bit and meet some locals. Any recommendations for a solo traveller?
I want to try places where locals go, not where many foreigners go like Roppongi and British/Irish pubs.

Thanks!

Shinjuku Omoide Yokocho street
http://www.shinjuku-omoide.com/english/

Shinjuku Golden Gai
https://www.roughguides.com/article/tokyos-tiniest-drinking-dens-a-gui...

They open at evening(after 17:00 - 18:00) until morning.
Those restaurants are mostly friendly for international visitors but not all of them, so be careful about your behavior.

Golden Gai is also the largest Gay town in JP, so be careful if you are a solo male visitor(recommend to visit with a group or friends).

Away from Shinjuku, you can try Yurakucho , under the JR Yamanote Line, also known in Japanese as Gado-shita.

https://www.japan-guide.com/e/e3072.html

You'll find a lot of dance halls, night clubs and bars dotted around just by walking around at night.

To the north east of Shinjuku station, there is a large entertainment district full of lights and glamour.

Thanks all for the answers, I'll check it out!