Sanja Matsuri (Three Shrine Festival), one of the three large Shinto festivals in Tokyo, kicks off with the religious ceremony on May 15 (Thursday). The festival is known to be one of the wildest and roughest in Japan. Even Yakuza are allowed to show off their full body tattoos, which are usually banned in most places in Japan.
Because of the roughness of the festival, people are not allowed to get on the mikoshi, and it was again reiterated after one of the main mikoshis were damaged in 2006. However, last year people again got on the mikoshi, resulting in 5 arrests. As a result, main mikoshis will not be used in the festival this year.
Around 1-2 million people attend the festival, including many yakuza members. Due to the restrictions on the mikoshi, there may be a drop in attendance, but there should still be quite a crowd. So if you are looking for some excitement this weekend, head on down to Asakusa.