Looking for recommendation for group workout near Shinjuku

Hi all! So starting today, I'm living in Tokyo for 6 months for school purposes. I want to start looking at places where I can work out. I exercised regularly for the last few months and am trying to gain some muscle & lose some weight.

I prefer places where there are group workouts as well – not only open gym, that way I'll be more committed to not slacking.

I'm living in Yochōmachi, Shinjuku, btw. But I don't mind taking a 15-20 minute train.

I'm looking at Google Maps near me, and mainly what I see are tiny gyms.

2 options that I saw so far that look nice are –

1. Gold gym – looks like it's an open gym + classes.

2. Orange theory – at least price-wise it's very premium – like 130$/month. But maybe this is something that will help me.

I would also really want to join a running group!

Any recommendation? Thanks!