Alright, finished with GTO... glad I decided to read it, I wonder why more hasn't been animated. No real loose ends, only that GTO's love life is never an issue...even after Azusa finally accepts that she's in love with him (but they don't do nothing with it). I like the Urumi pairing myself. Otherwise, it's a complete ending with Onizuka having everyone in school in his pocket by the end of it.

I was hoping for a sequel just so that they could touch on the above issues, but this seems more like a sidestory since it takes place after he was shot by the dude that kidnapped Azusa. Looking forward to it regardless.

The first scene of the manga though seems like it's right after the end of GTO, since it talks about it being 3 months ago, and I think GTO's storyline went only a couple of months after he got shot.

Though Kunio and the other dude look noticeable older in my opinion.