Who said anything about 'need' or 'responsibility'?

[ Yuji shakes his head, looking awkward all over again. ]

You're making it sound like this is some kind of mission or something. I'm being nice because it's the right thing to do, and it's the kind of thing that my grandpa would tell me to do as well. I'm not going out of my way to try and save you or anything?

[ A shrug. ]

We're here for the same reason - to help fight the kaiju. I don't see the reason in fighting each other when that's something to worry about.