I consider this premise more as a setup than as a "plot". Hmm...how can I compare this to. It's like The Simpsons. There's this average American family of 5. What's the plot of the Simpsons? I don't know, but pretty damn funny to watch about them. Same idea applies: There's this tough boy with a girl on his right hand. What's the plot? I don't know...but it's pretty damn funny to watch about him too. Oh wait, I guess the plot is Midori's love for Seiji, and romantic conflicts between them.
Spoiler:
Episode 5 was an average episode for me. Not to say it was bad, it's still funny. I never knew Seiji would have such a low tolerance to alcohol. One gulp of sake and he passes out? Not much of a delinquent to me.
. How long will this series run? I hope it's more than just 12-13 episodes. They haven't even started on Kouta yet...and that weird girl who has an unnatural interest in Midori. Who hoo, Rin's back in episode 06.