The donjon is connected to a smaller donjon or yagura by a watari-yagura. I picked Matsumoto Castle below as one example of a renketsushiki donjon, but actually Matsumoto Castle exemplifies both Fukugoshiki and Renketsushiki. The Inui Kotenshu is connected by a watari yagura, makiing it renketsushiki, but the Tatsumi Tsuki-yagura on the opposite side is connected directly to teh castle making it fukugoshiki.