Another nice thing to look out for is wasabi miso. Miso mixed with wasabi stems and used as a topping for tofu, rice or just as an otsumami. I got some at a tofu restaurant in Sawanoi in the mountains of western Tokyo. Also tried a wasabi cream cheese as well

Nice day trip by the way, Ozawa sake brewery has a little nice garden by the river, two tofu restaurants, one just drop in, one is reservations only. You can tour the brewery, reservations required, visit the tasting room l, nice coffee too.
Also hiking and bouldering and possibly camping along the tamagawa river.

and looking back at the map I found this, just up. Wasabi experience, offering a wasabi tour in English as well as Japanese. a great day trip beyond the far end of the chuo line.

https://okutamawasabi.com/wasabi_tour_en/