One of the biggest and most beloved fireworks festivals in Osaka, the Naniwa Yodogawa Fireworks Festival (なにわ淀川花火大会) has been held along the Shin-Yodogawa River every year since 1989, and despite its size, the festival is put on almost entirely by the local residents and businesses of the Juso neighborhood. Attendance each year is approximately 500,000 people, and the fireworks display is massive. The 2010 festival will be held on Saturday, August 7: the fireworks start launching at 7:50 pm and the show lasts until around 9:00 pm, but unless you have a reserved seat somewhere, I suggest bringing your tarp and staking out a place along the river in the afternoon if you want any chance of sitting. Most people dress up in yukata and have picnics beforehand, making it an all-day event.
The closest stations to the festival are Tsukamoto Station (JR Kobe/San’yo Line) and Juso Station (Hankyu Kobe, Kyoto and Takarazuka Lines). Admission is free unless you want reserved seats. The festival’s homepage (Japanese only) can be viewed here.
Note: Photo by Wikimedia Commons.