Nezu Shrine in Bunkyo-ku is always worth a visit, thanks to its wonderful historical buildings nestled down in the hilly landscape, the torii path, as well as the beautiful and detailed decorations of the main hall. However, the highlight of the year is the Tsutsuji Matsuri, or Azalea Festival, which takes place every year from around mid-April until the beginning of May, when the azalea bushes start to bloom. I definitely recommend to try and go during the week; it's much more charming without the weekend crowds... Enjoy!
Find out more about Nezu Shrine.