Ojii-chan wa 25-sai

46 years ago Kurihara Minoru went to the mountains to take pictures, but never returned. Fast forward to the present and he is discovered perfectly preserved in ice. He then miraculously wakes up. The head of the Kurihara household is now Kurihara Norihiko, who is Minoru's son and 52 years old. There are also Minoru's grandson Kensuke and granddaughter Mai. Their family is set for upheaval as their grandfather (who still looks 25, but is now 71) returns to their home.