The Song ( Kyō no Hi wa Sayōnara / 今日の日はさようなら), and the Actress (Tokiwa Takako).
I had not expected such meeting would happen twice, especially when considering that Tokiwa Takako is not a singer and she is not the performer who made it famous. After some research over the Internet, I found out that it is a 1966 classic by Moriyama Ryoko.
In the 1997 drama Saigo No Koi (最後の恋, Last Love), Tokiwa Takako sung it as a lullaby for her character’s younger brother, afflicted by a heart disease.
In the 2002 drama Long Love Letter (ロング・ラブレター), she sung it again. At that time, her character was one of the people who had unexplainably been transported several years in the future, to discover a barren and hostile Earth. The lyrics of the songs once again brought peace in the hearts of the listeners.
The song is actually beautiful and peaceful. Depending on your mood, it may make you feel nostalgic or fill your heart with hope.