Something has been happening in jdoramaland and that is spin offs. I'm not sure when this started but many shows like Ukiwa Tomodachi Ijou Furin Miman have spawned the spin off Ukiwa Tanin Ijou Tomodachi Miman and they seem to be increasing.
I would imagine one day a producer was thinking since we already have a B team shooting supporting stuff for a dorama, why not extend the shooting time and create a side dorama and the tv station can cheaply fill up another 20 minutes of tv time?
I think this is a bad idea because side stories are very important to jdoramas. The side characters keep the audience from being bored with the main characters. The side characters don't have as much depth but they get to say and do things the main characters cannot.
I am afraid that writers might leave stuff off the main story and save them for the side because watching Tanin Ijou Tomodachi Miman, there is nothing really there to do. On the other hand, some people might not mind because they get to see more of their supporting characters and this gives them more acting practice.
I think I have only tried another spinoff, can't remember which but I don't like where this is going. It could be harmless and there is no need to watch them but I feel like the resources should be concentrated on the main story.