Chiba finally won her first women's professional shogi major title in June 2005 when she defeated Nakai 3 games to none to win the 27th title. The following year, Nakai once again challenged Chiba in the 28th Women's Ōshō title match, but this time it was Chiba coming back to win Games 4 and 5 to successfully defend her title 3 games to 2. Chiba defended her Women's Ōshō against Shimizu in 2007 and started well by winning Game 1, but Shimizu won the next three games to capture the 29th Women's Ōshō match 3 games to 1.
