This is the last day of the three day weekend (today is a national holiday in Japan, coming of age day). So it's safe to say it's pretty dead compared to yesterday or the day before yesterday. However, I am sure certain "sightseeing" bars are not too empty for sure. At Arch, there is the drag queen themed event tonight until 11pm so it might be fun for you to check it out and start from there.

Safe travels.