This was interesting. Turned up when I searched google for "ancient romantic love in Japan:"

In Japanese Buddhism, ai (愛) is passionate caring love, and a fundamental desire. It can develop towards either selfishness or selflessness and enlightenment. Amae (甘え), a Japanese word meaning "indulgent dependence," is part of the child-rearing culture of Japan. Japanese mothers are expected to hug and indulge their children, and children are expected to reward their mothers by clinging and serving. Some sociologists have suggested that Japanese social interactions in later life are modeled on the mother-child amae.

Also, some interesting stuff in THIS BLOG.

And, from THIS SITE:

Note: While the Japanese language uses the same characters, this phrase would not be spoken - it's kind of taboo in Japan. A man might tell a woman that he likes her with the phrase "Watashi wa anata ga suki-desu" (I regarding you have liking). If your audience is Japanese, avoid this "I love you" phrase. If you need something special, we have a Japanese translator on call.

And, one more because I find this really interesting!:-)

from HERE:

the two most common words for love are ai （愛）and koi (恋). Generally speaking, most forms of non-romantic love are expressed using the former, while romantic love is expressed using the latter. "Parental love", for example, is oya no ai (親の愛), while "to be in love with" is koi suru (恋する). There are of course exceptions. The word aijin (愛人) means "lover" and implies an illicit, often extramarital relationship, whereas koibito (恋人) has the connotation of "boyfriend", "girlfriend", or "partner".

In everyday conversation, however, ai (愛) and koi (恋) are rarely used because to many Japanese people the word "ai" sounds either overly dramatic or desperate. Rather than using ai shiteiru (愛している) or koi shiteiru (恋している) to say "I love you", for example, most Japanese would say daisuki desu (大好きです), which means "I really like you" -- suki (好き) being the same word used to express preferences for food, music, etc., as in sushi ga suki desu (寿司が好きです), or "I like sushi." Rather than diluting the sentiment, however, the implied meaning of "love" is understood. (The phrase ai shiteiru (愛している), "I love you", however, tends to show up frequently in pop song love ballads.)

Good luck and have fun!