How come the wife of Okakura Daisuke, the fifth part of "Cold and Warm", has disappeared?

You are talking about the passage in the fourth TV series. The actress Okakuro also died of gallbladder cancer in 1999, so she died of a heart attack while traveling in the United States. Incidentally, Takuya Fujioka, the actor of Okakura Daisuke, also died in 2006. So you'll never see him again when you watch the eighth film.