This drama is based on a 1997-98 manga with the same title by Ishizaka Kei. It was made into a 20-episode drama in 2014 on NHK starring Tokitou Saburou, Kon'no Misako and Toda Naho. The current one is shown on TV Asahi.
(Spoiler)
An accident causes Ieji Hisashi (played by Kimura Takuya), an elite businessman in a stock-trading company to lose his memory. A strange thing is that he remembers things that happened more than 5 years ago. After his divorce 5 years ago, his memory is blurred.
After a long stay in a hospital and going through physical therapy, he goes back to where he was with blurred memories. He has 10 keys on his key chain, but he does not remember what they are for.
He goes home, but it was the home of his ex-wife (played by Mizuno Miki) and their daughter (played by Yamaguchi Mayu). The ex-wife and the daughter tell him about the mistake and send him to his new home. Hisashi returns the house key to his ex-wife. So now, the mystery keys are 9.
Hisashi remarried Megumi (played by Ueto Aya) and lives with her and her son from her previous marriage. Whenever Hisashi sees Megumi and the boy, he sees masks on their faces. He cannot see their facial expressions.
Probably because Hisashi has more vivid memory of his former family, he feels that family was warmer with love. He feels somewhat out of place when he is with his current family. Nevertheless he tries hard to love them and be a good father/husband.
At work, he used to be an elite businessman. Now he does not remember how to do and what he is supposed to do, the company moves him to a minor division. His colleagues are those the company does not expect anything from.
One night he meets a man (played by Kagawa Teruyuki) has a drink together. The man is from a client company and the two worked together, but of course, Hisashi does not remember that. The man is about to be fired and shows Hisashi his anger and sadness. Hisashi tells him that he was dead once, and now he doesn't know anything. Even a young woman in his office scolds him. It was his way of telling the man that he was not alone.
A few days later the man comes to Hisashi's company with a large project contract. He is an executive managing director, and that was his last project in his company. He appoints Hisashi as the person in charge. Suddenly, Hisashi and the minor division to which Hisashi belongs step into the spotlight.... (end of ep.1)
It's a fun story with mysterious elements. Good casts. This is likely to be a hit drama for this season.
