Fufu, but of course! To me, you're rather like a puzzle, itching to be solved. Rest assured, regardless of my success rate, I'll be working day and night to find a workable solution for you for as long as it takes.

[He says this all plainly, like it's not a big deal at all. Which might make it sound like he's lying but--]

[Well, assuming Chuuya trusts that he's upholding his side of the deal, he'll know that Mephisto can't lie to him anymore.]

But I can't say I'd have a reason to tell anyone, no. There may come a time in the future in which I'd like to be able refer to you as one of my familiars to those I consider my closest allies-- but if this is something you wish to keep secret, I will honor that to the best of my ability.