STD Testing in Tokyo

[cherrysakura]

I live in Japan and I had unprotected sex and need to get tested from STD's as soon as possible. Does anyone have advice about where I can?
When I google it I can only get very outdated information.

Shinjuku Health Center - AIDS and STD test center/Tokyo Health & Medicine, Clinic-Others - Sunnypages.jp
I know about this health center, but I have class during that time on thursday that I cannot miss..

Relevant information:
I am Female
American
20
I live in Shibuya ward
I speak only very basic Japanese

Thank you!