People keep taking those words out of context - I assume you haven't read that part in manga? He said that as a figure of speech in reply to Yuki:
Y: I can't live without you
M: Well can you die for me then
You realize what he did right, flipped a phrase as a mockery for the cheesy argument because it wasn't ringing true for him. We didn't have any even remotely close sentiment in that to actually ask Yuki to kill himself.
Yeah we need to be careful of what we say to each other, every time people say KYS just gives me a big shudder. But there is literally nobody who blames and hates Mafuyu more for this than Mafuyu himself. He said that in a moment of anger but they also kept arguing for a while at that point. Mafuyu is obviously a very gentle soul, he deserved not to be dismissed as a one-dimensional character, as well as the rest of this cast and the story. People are complicated beings, there are a lot of things that at odds inside us, you can't judge and wish the worst on someone based on a phrase taken out of context - this stands for real life too. I don't think you are trash, just a bit naive and quick to jump to conclusions. I hope you can reflect on this more and be smarter about how you judge people's character and be able to find more empathy inside yourself.
I won't do that if I were you... People are fragile and always makes mistakes.. Mafuyu is just an example.. sometimes, people having trouble finding the right words to express their feeling, thats why TIME is there, make some effort to understand and avoid judging a situation in a negative way.. I think that's what sensei wants to tell us.. and as good friends, Hiiragi and Shizu shoud not leave them alone after that argument... when Yuki's alone, he turned to alcohol for solution... Not Hiiragi, not Shizu, there are a lot of things we can learn from this show... there's no such thing as mind your own business.. we meddle because we care.. Killing yourself doesn't end things.. more sadness, sorrow and regrets were left behind, and more death may follow on suit.. Uenoyama may come as new love and hope that Sato needs as the reason to live... So, PLEASE,,,, TREASURE YOUR LIFE... there are always tears falling afterwards...
people don't commit suicide because you said something mean to them. there isn't one specific reason yuuki killed himself.
and after knowing the reason of yuki's death I can't keep watching it because until knowing the reason I always felt pity for Mayufu but now I can't sympathize him anymore so I'm just gonna drop the Anime and the manga I'm not gonna read it till the end because Uenoyama is too precious for him 'who knows Mayufu can do the same thing again with his feelings too' officially I'm Mayufu's hater now. Everyone can say I'm a trash, I'm not a human being but everyone has got their own right to say the things not to the point of causing the death of someone