So I'm heading to Japan for the TGS (mostly a pretext, I don't expect anything much for the TGS anymore sadly). We are staying at an airbnb apartment right next to the Sendagi station, 10 minutes walk from Nippori on the Yamanote line. I hear that part of Tokyo is pretty calm and nice, so I'm looking forward to being there

I've been to Tokyo many times now, so I'm looking for stuff that's I've not seen before but worth checking out. I've been to basically all the most popular spots for tourists (shibuya, shinjuku, roppongi (meh), asakusa, skytree, yoyogi, ikebukuro, ginza, odaiba, kamakura, ueno, aikiba, takao and maybe others I forgot). I especially like gardens/nature, so anything worth checking in or around tokyo (let's say 90 minutes max from a Yamanote station)?