Construction of Ninomaru Shinchi and Yatsushiro Shinchi, completed in 1855 (Ansei 2), found work completion difficult, so several strong female sumo wrestlers from surrounding villages stomped on the tide gate to safely finish the work. Since then, in the Ninomaru district, prayers are offered at Ryu (Dragon) Shrine where sumo wrestling is dedicated at its annual festival. While it is not known when women became the center of "women's sumo", it is now preserved by the Women's Sumo Preservation Society. Following rituals at Ryu Shrine, dotsuki (ring entrance ceremony), sumo jinku (a sumo-themed group chant), rikishi (sumo wrestler) introduction, yokozuna dohyo entrance, bouts, and finally a yumitori-shiki (the bow-twirling ceremony).