There are many interesting places to visit in Japan. If you don't have a lot of money to move around the country and you plan to focus on Tokyo and its surroundings, I have a proposal for you: travel a little further, even for one day, and visit Hiroshima. You can get there in a few hours using the shinkansen, the Japanese bullet train.
Hiroshima bears the sad title of being the world's first atomized city: On August 6, 1945 at 8:15 a.m. an American bomber dropped the first atomic bomb used in a war. It is estimated that between 90 and 166 thousand people died between the explosion and the subsequent radioactive effects. Visiting Hiroshima and its museum and memorial park makes your skin crawl.
There are classic postcards of Hiroshima, like the half-demolished building, the Bell of Peace and the profile of the museum. A plaque is also hidden there that marks the zero point of the explosion: it contains an image of the disaster and people often leave flowers and paper cranes in memory of the dead. It is only a five minute walk from the ruined building.
The entrance to the museum is not charged, it just has a minimum fee that is requested as a collaboration. Inside is the history, maps, photos, objects and much more about the hiroshima explosion and its victims. There are jars that show the deformations produced by radiation, a section that shows what happened to metals, wood, stones and glass in the heat wave, there are videos, photos and many personal effects that were found among the ruins of this city. Japanese that today, except for this park and museum, is like new.