The G3 symbol is pretty rad. If you look in the center, you can see the Japanese police symbol, the order of the rising sun. This is also known as the sakura crest as well as many other names.
This is the weird episode that's 4:3 in size. Also unusual in that it was written by Kobayashi Yasuko (main Go-Buster writer). The rest were written by Inoue Toshiki (who's writing that new show with director Amemiya Keita).