https://www.japan-guide.com/e/e2030.html
The Tokyo Central Hostel is Iidabashi is a good location. http://www.jyh.or.jp/info_e.php?jyhno=2618
Information on budget accommodation. https://www.japan-guide.com/e/e2028_accommodation.html
A couple of suggestions.
https://www.insidekyoto.com/best-budget-hotels-in-kyoto
https://www.tokyoweekender.com/travel/the-10-best-budget-hotels-in-tokyo/
Don't choose Kinugawa Onsen if you're visiting Nikko. It is too far away.
There is also Turtle Inn but I was quite surprised with the price.
Do you want to communicate with others or are you just trying to find a cheaper place?
Edited: 10:13 am, May 06, 2024Thank you!
I'm helping my kids do research on Hostels. They want to stay at an affordable place with young adults their age.
Hostels won't have age limitation so I cannot guarantee that the guests will be their age.
There is another one at Nikko really close to the station. I will ask my friend about its name soon.
There are also some at Ryogoku, Kuramae and Asakusa. I think Grid Hotel and Hostel Ueno is a great location.