What season and episode is the death of Dr. Delong?

In the 31st episode of Crayon Shinchan, Dr. Delong died in the 31st episode. Dr Delong went to a foreign country and was killed in a terrorist attack. "Crayon Xiao Xin" tells the story of Xiaobai, a 5-year-old child from Xiao Xin, who adopts a stray dog like cotton candy and often tells some boring jokes. Xiao Xin's mother is a full-time housewife. She is careless and a little neurotic. She is often laughed at by Xiao Xin, and her father Nohara is often confused by these two mothers and children.