Thanks for the responses people!
Oh it's not a silly question; it's a really interesting thought experiment. I only meant it's important to have in mind that assessments on who objectively possesses a particular trait the most are not really going to be possible, but subject to personal interpretation (see also: power level discussions), because there's no objective way to measure it. I mean, we can safely say "X would be high up there" but not "X is at the top".
Hm, saying 'the most' would make it sound like I was looking for an objective pinnacle. I was just looking for any character with a desperate yearning really. A few characters have it in their background stories, now that I have more time to think about it: Kaguya wanted to go to earth, Mokou wanted revenge against Kaguya, Yuyuko wanted to die, I think I had one more but can't remember it.
Whoever suggested Kasen, I think that's a top contender for present day people. Though I can't really do much with that...
Koishi too, is good suggestion. She's just tragic in general. I think maybe she too had a strong desire to be liked by everyone, which may be why she closed her eye.