Only by seeing him with your own eyes...
Could you be sure?
Then what if this Hada Ichiba was not Taki Chiba, but merely related to him? After all, the Hada Clan that had appeared out of nowhere seemed to have quite a deep connection with Taki Chiba.
This Hada Ichiba was related to Taki Chiba, and perhaps he was even a double Taki Chiba had found who looked exactly like him.
Indeed, that made sense.
Still, it felt like an endless deadlock. Hada Ichiba's identity seemed to have become a mystery once more.
Following that line of reasoning, could that be why Hada Ichiba had so readily admitted that he was Taki Chiba?
Simply admitting that he was Taki Chiba still left many possibilities.
One possibility was that Hada Ichiba truly was Taki Chiba, but letting them know that Hada Ichiba was Taki Chiba was part of Taki Chiba's objective. In other words, announcing his own name was part of his plan. Whether they knew or did not know might be irrelevant—or it might be crucial.
Taki Chiba wanted them to know of his existence. His appearance in the Chunin Exams, and perhaps even the series of reactions that followed once they learned he had appeared in the Chunin Exams, might have been what his plan required.
Another possibility was that Hada Ichiba was not Taki Chiba at all, that this was merely a pretense. Hada Ichiba might be a smokescreen, drawing their attention so that he could complete his plan in secret.
Yet another possibility was that, regardless of whether Hada Ichiba was Taki Chiba, Hada Ichiba claimed to be Taki Chiba precisely so they would waver as they were now, so they would question whether he was Taki Chiba and fall into this uncertain frame of mind.