When the six cast members of the hit American comedy series "Friends" recently agreed to a 10th season, no one was really surprised, even though the six had implied that the present season would be their last.

After all, each actor receives $1 million per episode. Since each episode costs $9 million to produce, that means two-thirds of the budget goes to the cast. The economics imply that it's the actors who have made "Friends" a success, but situation comedies are group-intensive endeavors. Over the past decade, the six actors have developed characters that viewers have come to love, but they couldn't have done it without scores of writers who have helped shape those characters with funny lines and situations.

It is this long-term collective aspect that has prevented the situation comedy from taking root in Japan. Over the years, American imports such as "I Love Lucy," "Bewitched" and even "Friends" have been popular here, but they never spawned local equivalents the way cop shows and medical dramas have. Most Japanese TV shows are built around one or two famous people, be they performers or writers, and they are conceived for short runs.