Lodging in Tokyo in August is at a premium. The Congress strongly recommends that you book as soon as possible!
Note that the further the hotel is from the central areas of Tokyo, the cheaper the rate will be, so if price is an issue, you might consider a longer commute in exchange for a lower rate.
Here are some online services that you can try. When searching online, the station closest to Toyo Gakuen University is “Suidobashi” (水道橋).
If you are visiting Japan and are interested in a ‘cultural experience’, committee member Joanne Sato<email@example.com> is willing to place a limited number of participants with Japanese families. Note, however, that these accommodations will most likely be in the suburbs, and thus might entail a commute of one hour or more. If you are interested, please make your request by June 30.