One click install (only supported by versions mentioned below):

• Tachiyomi v0.15.2+
• Tachiyomi Preview r6404+
• TachiyomiSY v1.10.0+
• TachiyomiSY Preview r539+
• Aniyomi Preview r7443+

TachiyomiAZ:

1. Go to Settings → Browse
2. Tap on "Edit repos" and then "Add" button at bottom
3. Input keiyoushi/extensions
4. Enjoy!

If you're not using any of the above, download and update extensions from the listing page.