In Japan, the celebration was introduced in 1936, when the company Morozoff Ltd. run an advertising campaign (that was actually intended for foreigners).
Later, in 1953, a promotion of heart-shaped chocolates appeared and in the following years, the Japanese specific custom for women to give chocolates to men on Valentine's Day also appeared...
I don't know how you plan to spend this Valentine's Day, but if I would be in Tokyo today, besides giving the hearth-shaped chocolate to my husband, I would take him to the World Trade Center Observatory, to take a hearth-shaped photo of us... with the Tokyo Tower in the background...
P.S. This photo is not a Photoshop, the window really has this hearth-shaped decoration!
EXIF info:
Nikon D90
Lens: VR 18-55mm F/3.5-5.6G
Focal Length: 18mm
Aperture: F/7.1
Shutter Speed: 1/500s
ISO Sensitivity: ISO 200