A dismissive gesture of his hand, almost a fioriture accompanied by a noncommittal shrug. He was no point in beating around the bush about this, there was one singular thing that Overhaul had that could interest the League. Running in circles around each other might be entertaining for those who enjoyed said mental games, and although Tomura recognized those could be useful sometimes, he preferred a more direct approach most of the time.
"Well, aren't you a humble guy?" he could see it, of course, the pride and satisfaction, and if what he said was true then Tomura wasn't about to say it wasn't well deserved. Even Dalma, with his fancy laboratory and decades of research hadn't come close to create anything like those bullets. If Chisaki wanted to strut around like a slightly less fancier peacock, so be it.
"I'm not surprised, but I will admit I didn't think it was that bad. I'll give it to you, pretty impressive for your situation." +1 respect, he makes a inner note, "I assumed you guys where lacking on something, otherwise we would've been seen lots more of you. We all know the yakuza isn't doing big numbers lately, and if you weren't in a tight spot you wouldn't be bothering trying to make alliances in first place."
Anyone could put two and two together. It wasn't any different from piecing lore scattered in item descriptions. That was harder, actually. Yet, there was also the fact that Chisaki had no way of knowing that Tomura had exactly what was needed to make this into a fair item exchange. He probably only intended to obtain some measure of manpower from the league, maybe some notes from the old man if he was lucky, but this? He hit the jackpot and didn't even know it. Fate— providence, Sensei called it, seemed to have a hand at work. If he didn't know any better, he would have suspected some kind of informant— a traitor playing for both sides; it was all just that perfect. Chisaki had something Tomura wanted, and he didn't know it yet, but Tomura had exactly what he needed to make this a fair item exchange. However, if there's one thing Shigaraki Tomura has is trust in his comrades; this was just a lucky, perfect coincidence.
"Alright then, I'm about to make your day— no, scratch that. More like your damn year. You, Overhaul, have the research; put it on the table. I have the means. I've a specialist, I've the facilities. I've your damn DLC." he extends his arms outwards, as if bathing in praise, any similitude with All for One was purely coincidental, thank you, "Bet you didn't see that one coming, huh? Call it Steam's Christmas sale. All off. See? I can be humble too."