Tony's humored smile fades as Manabu latches on the poorly chosen remark. Oh. Right. That.. well.. guess he's told enough people anyway..
"Don't let this get back to Peter. I'm from his future, assuming we're actually from the same universe and not just similar ones. Some really bad things are going to happen and one of those things is a being from some other reality comes and wipes out exactly 50% of everyone on Earth, my home planet. Right before I came here we were fighting him again and I was just about to kill him and bring everyone back he destroyed when I showed up here. Peter's one of the ones who gets taken and there's nothing he can do about it, so I don't want him to have to live with that fear. But if for some reason I don't succeed in what I was doing- if I don't kill Thanos- then our world will be destroyed. If I win, then I die. He doesn't need to know that either."
Endgame Spoilers
"Don't let this get back to Peter. I'm from his future, assuming we're actually from the same universe and not just similar ones. Some really bad things are going to happen and one of those things is a being from some other reality comes and wipes out exactly 50% of everyone on Earth, my home planet. Right before I came here we were fighting him again and I was just about to kill him and bring everyone back he destroyed when I showed up here. Peter's one of the ones who gets taken and there's nothing he can do about it, so I don't want him to have to live with that fear. But if for some reason I don't succeed in what I was doing- if I don't kill Thanos- then our world will be destroyed. If I win, then I die. He doesn't need to know that either."