Tokyo Tower

Toru, a 20-year old man, falls in love with a woman who is not only married but also 20 years older than he. Complicating matters even further, she also happens to be a good friend of his own mother. Not the makings of a simple relationship, to say the least. For her part, the married woman has all the money and possessions she could ever want. But something is missing, and it is that "something" that she finds in this very unexepected yet undeniable love for a man young enough to be her own son. The story unfolds in tandemwith that of Toru's friend, Koji, who also falls in love with a married woman. The two couples struggle to deal with the complexities of modern relationships, in an effort to find a balance between the forces of true love and the reality surrounding them.
(Source: AsianWiki)
~~ Adapted from the novel "Tokyo Tower" (東京タワー) by Ekuni Kaori (江國香織).