I'm sorry, I'm not familiar with a specific 'oingo boingo little girls story'. It could be a very unique or perhaps a rather unknown story. Maybe it's from a particular local folklore or a very specific piece of literature.
Since I don't know the actual 'oingo boingo little girls story', I can't say for sure about the characters. But generally in a story about little girls, there could be the little girls themselves as main characters. There might also be their parents, friends, or some sort of antagonist like a mean neighbor or a magical creature causing trouble.
The JJBA manga is indeed finished. It had a great journey and wrapped up with a satisfying conclusion for fans. However, there's always the possibility of spin-offs or related works in the future.
There's also 'Diamond in the Rough'. This fanfic focuses on a unique relationship between the reader and a JJBA character. The writing style is very descriptive, especially when it comes to the Stand battles. It really brings the action to life and makes you feel like you're in the middle of the chaos.
Some JJBA fanfics that are worth reading are the ones that expand on the battles. They might add more complex strategies or new foes that the characters have to face. For instance, a fanfic could introduce a new stand user who has the power to manipulate time in a different way than Dio. Also, fanfics that give a different perspective on the existing story arcs, like seeing the events of Stardust Crusaders from an enemy's point of view, can be quite engaging.
One interesting JJBA gamer fanfiction could be about a gamer who gets transported into the JJBA universe and has to use their gaming skills to survive the Stand battles. For example, they might be really good at strategic planning in games, and they apply that to outwit enemies with Stands.