Daimonji is the name of the character in this photo, the meaning of this character is "big" or "great". There are actually three characters and two symbols on the sides of mountains that are set alight on the night of August 16th every year to mark the end of the Obon season. The name of this festival is Gozan no Okuribi, but people commonly refer to it as Daimonji. While there is only one each of the other two characters and the two symbols, there are two giant Daimonji on the sides of mountains in Kyoto. The one in this photo is the one near Ginkakuji (the Temple of the Silver Pavilion). The other Diamonji is near Kinkakuji (the Temple of the Golden Pavilion).
The spot most people go to get a close view of three characters is along the Western bank of the Kamo River (Kamogawa) between Sanjo-dori and Imadegawa-dori. To see the two symbols as well you really have to go on the roof top of tall a building. The Kyoto Tower actually raffles off tickets to view the fires from there, but it's quite far from the fires. Another place people go on the 16th is to the Hirosawa pond in Arashiyama. I think only one of the symbols is visible from there, but there are many floating lanterns placed in the pond.
I took this photo last year, it was my first time to view the festival. There were a few rain showers that evening, but we enjoyed ourselves and had some nice conversations with people we meet in the crowds. After the fires went out, we found a nice restaurant near the bridge on Sanjo-dori and had dinner.
The photo was taken handheld with a Nikon D700 camera and an AF-S VR Zoom-Nikkor 70-300mm f/4.5-5.6G IF-ED lens. It was captured as a RAW (.NEF) and post processed in DxO Optics Pro. I made the following adjustments: Default Camera and Lens Corrections; DxO Smart Lighting (25%); Prime Noise Reduction; and Cropped to 5:4 ratio.