Jin Kobayashi/Kobayashi Jin /小林尽 or KJ for short in some forums. Is the well known author and artist of the manga called School Rumble. His distinct likeness to the main male protagonist Harima Kenji made people interested in him. Many rumors sprung that he has a half American wife which is blond, who looks similar to Eri the half Japanese/American girl in School Rumble which is the most popular pairing for Harima. But as he said he want's to lay low and have a low profile, but it was too late after his public appearance looking EXACTLY like the main guy in School Rumble, though he said that Harima is only partly percent modeled after him and other characteristics are modeled after his friends. Harima is great at basket ball and on a side note KJ plays basketball whenever he's not doing manga and speaking of basketball and friends did you knew that Takeshi Kusao the voice of Hanamichi Sakuragi from Slam Dunk is his friend?
Though when School Rumble ended many trolled, flamed, bashed and basterdized the poor guy, including yours truly. lol. Since many fans where not satisfied with the ending KJ gave the fans. Thus for a saving grace for his masterpiece he created a new School Rumble Manga entitled School Rumble Z. Which has more gags and has no plot. It's funny non the less, but the fans wanted the story and answers to the pairings and plot. Ironically on SRZ chapter.3 Jin Kobayashi kinda, indirectly explains his well being. As chapter 3 of SRZ starts with a poor depressed mangaka Harima(similar to KJ after the end of SR for not satisfiying the fans), which he turned into a professional baseball player due to "some lucky Fish Bone Pen" then losing everything because Tenma called him and he dropped his cigar and burn all his life, putting him in the same spot as the start. All that was left was his fish bone pen and Harima said to himself that. "I may have lost everything, but still I still can be a mangaka...". Which is ironically similar to his old interview that he was asked a question that if was not doing manga what would he'd be. He replied that he'd be an illustrator or anything related to manga and drawing since he loves to draw. KJ's main inspiration is Dragonball, one reason also for Harima to turn into a saiyajin monkey ape in one of the chapters of SR, also the anime and manga featured Harima turning Super Saiyan.
And so what else I can conclude about Harima and KJ? Well I guess hints and bits of his personal life is in the SR and SRZ manga which is secretly puts indirectly. SRZ manga is now at chapter.4 which features a young Harima, Tenma and Yakumo. Which is a flashback to the School Rumble manga. Seems KJ has been listening to fans and created a chapter which is within the School Rumble universe and not a spin off.
More on KJ's work and personal life on Wiki.