Q:Please answer the following question about this movie plot. If it's un-answerable, please output "No answer". Question: Who is th couple's younger son? Movie plot title: Tokyo Story Movie plot: A retired couple, Shukichi and Tomi Hirayama (played by Chishu Ryu and Chieko Higashiyama respectively) live in the town of Onomichi in southwest Japan with their daughter Kyoko (played by Kyoko Kagawa). They have five adult children, four living. The couple travel to Tokyo to visit their son, daughter, and widowed daughter-in-law. Their eldest son, Koichi (So Yamamura), is a pediatrician, and their eldest daughter, Shige (Haruko Sugimura), runs a hairdressing salon. Koichi and Shige are both busy, and do not have much time for their parents. Only their widowed daughter-in-law, Noriko (Setsuko Hara), goes out of her way to entertain them. She takes Shukichi and Tomi on a sightseeing tour of metropolitan Tokyo. Koichi and Shige pay for their parents' stay at a hot spring spa at Atami, but the parents return early because the nightlife at the hotel interrupts their sleep. When they return, Shige explains that she sent them to Atami because she wanted to use their bedroom for a meeting. Tomi goes to stay with Noriko, whose husband, her son, died eight years ago in the war. Tomi advises Noriko to remarry. Shukichi, meanwhile, gets drunk with some old friends, then returns to Shige's salon. The couple remark on how their children have changed, and they leave for home, planning to see their younger son Keizo when the train passes through Osaka. Though they originally had planned to see him without leaving the train, Tomi takes ill during the journey and they decide to disembark, staying until she feels better the next day. However, when they later reach Onomichi, Tomi becomes critically ill. Koichi, Shige and Noriko rush to Onomichi to see Tomi, who dies shortly afterwards. Keizo arrives late as he is out-stationed. After the funeral, Koichi, Shige and Keizo leave immediately, with only Noriko not returning. After they leave, Kyoko is angry with them and complains to Noriko that they are selfish to their family. She believes that Koichi, Shige and Keizo don't care how hard it was for their father...
A:
Keiz