To elaborate on something, 'murim' is a korean term that refers to a concept that is most simply defined as "the world of martial arts." It crops up frequently in certain series, and is a near omnipresent concept in all manga and manhwa that deal with martial arts. The basic gist of it is that the martial arts community is insular and self-contained. They have their own feuds, alliances, and boundary lines, and as a point of honor, they keep those lines and relationships separate from the rest of the world, who are as a whole unaware of the existence of those relationships and connections. Thus, the serious martial arts world exists in a kind of underground, or Martial Arts World, that functions beneath the surface of the normal one. It has it's own traditions, rules, expectations, and etiquette, which can potentially run parallel to the real world, or it might run at an opposite grain entirely, depending on the story.
To call it a masquerade would not be entirely correct, because a masquerade is typically maintained at great pain and expense. Murim, by contrast, is maintained more or less solely by the discretion of the martial artists, who do not openly flaunt their powers unless strictly necessary, do not intervene in non-murim affairs, and do not openly advertise themselves. They keep their dealings in back alleys, private dojos, and behind closed doors. Though certain series, like The Breaker, can turn it into a full blown masquerade for the sake of drama. Often this is some necessary bleedover, because in high powered series like Veritas and The Breaker, a serious fight between martial artists has the potential to bring down buildings and tear a street apart, so public ignorance would have to be maintained through actual conspiracy, and not just discretion.
The Breaker refers to Murim directly and by using that term specifically, but it exists in Ranma, History's Strongest Disciple, Change 123, Veritas, Tenjo Tenge, and many other martial art series.
Given the way this particular setting of Love Hina is structured, Murim already exists here. All of the signs are there. Clans are wealthy, old, and have a kind of political power that the common person would be totally ignorant of, but individuals in positions of power (like politicians or, in this specific case, Police Commissioners) are aware of and respect intensely. Because of his connections, Keitaro was able to do and get away with things that a normal person never could (like owning a gun in Japan, starting an international incident and brushing it off, ect). The interactions between Keitaro and Tsuruko clearly show a self-contained culture of expectations, etiquette, and rules that someone who was not raised in one of the families would struggle to follow and understand, and the clans themselves seem to behave more like small, autonomous, militant states than families.
All of these are symptoms of a murim, which, as I've said, already seems to exist here. It just hasn't been explicitly mentioned by anyone directly.
tl;dr, my point is that, while you certainly don't have to do or acknowledge any of this, one possible point to consider for future plot is the idea that the Triad or other criminal elements that were present at Ronapur seek retribution against Keitaro for what he did, and the murim, as a whole, opposes that. Even clans that might traditionally oppose or have feuds with the Urashima could support Keitaro in this, because they exist in murim, the Martial Arts World, and don't want any interference from the criminal world, which would be seen as impinging upon murim's territory. They would support Keitaro as a matter of principle, which could lead to interesting plot developments, as well as physical and political conflict down the line.
As ThreadWeaver mentioned, one possible route it could go is the Aoyama deciding to give Motoko one last chance at redemption by assigning her as a personal bodyguard to Keitaro, thereby placing her back at the inn and providing suitable fodder for drama and humor in the process.
By the same token, it would also provide an extremely easy way to slip in further cameos from other series (if you so desired), and would provide the perfect excuse for the occasional action sequence as Keitaro is forced to fend off attacks from the Yakuza and foreign criminal elements.
Again, you don't have to use any of this, but I just felt that it was worth mentioning as something to possibly consider.
[EDIT]
Also, for the sake of completion, I should probably mention that Street Fighter is implied to exist in a murim context as well, albeit one that is not trying terribly hard to hide. It's a bit fantastical though, and much like Ranma 1/2 and a few other series, doesn't seem to concern itself too much with the details of the world that surrounds it, as it's entirely too busy having fun with bright colors and ridiculous fights. You see murim crop up more strongly in series that make a serious stab at having super martial arts exist alongside the normal world. Ninja Gaiden, Veritas, History's Strongest Disciple, and Change 123 are all good examples that convey murim to various degress (Ninja Gaiden being unique in that it has murim coincidentally existing alongside a World of Darkness style masquerade of the supernatural). And The Breaker, of course, has murim play a central role in the entire plot of the series.
