Question:
Who was the head of Ōsaka Prefecture in Oct, 1997?

Context:
 Hirofumi Yoshimura is the head of the government of Ōsaka Prefecture from Jan, 2019 to Dec, 2022. 
 Knock Yokoyama is the head of the government of Ōsaka Prefecture from Apr, 1995 to Dec, 1999. 
 Ichirō Matsui is the head of the government of Ōsaka Prefecture from Nov, 2011 to Mar, 2019. 
 Tōru Hashimoto is the head of the government of Ōsaka Prefecture from Feb, 2008 to Oct, 2011. 
 Fusae Ōta is the head of the government of Ōsaka Prefecture from Feb, 2000 to Feb, 2008. 
 Kazuo Nakagawa is the head of the government of Ōsaka Prefecture from Apr, 1991 to Apr, 1995.

Answer:
Knock Yokoyama