The 18th NHK Yorudora is Tokio, based on a 2002 science-fiction novel by Higashino Keigo, the same author who wrote Byakuyako.
The painful tears and deep emotions of the bonds between father and son transcend time in this epic, heart-warming drama.
The year is 1979, and Miyamoto Takumi's life suddenly changes when he meets a mysterious young man named Tokio at a park in Asakusa. The young man says, "I've come fromthe future. I'm your son, Tokio." Thinking it's some kind of bad joke, Takumi doesn't believe him at all. However, Tokio can predict the future, make strange machines, and shows Takumi strange powers. Takumi, who at first doesn't pay any mind to Tokio, slowly begins to believe him.
Present day, 2004. Miyamoto Tokio is suffering from a serious illness and is in between life and death. As 50-year-old Takumi watches over Tokio in his sickbed, he suddenly remembers strange happenings that took place 25 years ago...
A father and son who cross the borders of space and time to meet 25 years in the past; 1979. They travel together to Tokyo, Nagoya and Osaka, searching for Takumi's lover, Chizuru, who has disappeared. Takumi, who had been a bitter man, begins to grow as a human being through spending time with his son, who came from the world of the future. Throughout a strange two-week journey together, Tokio watches his father in his younger days, and leaves him with an encouraging message.(https://mydramalist.com/2334-tokio)
OAL: this was a sweet drama that.