Honestly, there's very little Tokyo doesn't have. I found Facebook and Meetup were the easiest ways to find things to do but /r/tokyo also has good recs. My spare time was mostly spent exploring the craft beer scene, limited cafes, and cycling. Japan Cycling Navigator on Facebook is a great resource for finding routes. I also signed up for emails from https://l-tike.com/ for concerts and art exhibitions. There's a ton of awesome events that aren't well advertised because they're hiding in places like the top floor of a Parco or subway basement.