[Listen, as far as Lief knows, he's unintentionally damned nearly literally everyone he loves back home to death, so he's not really in a position to judge for not doing enough for others??

He knows that telling Akira not to hold it against himself (even if he's thinking that) won't do a thing, since Akira won't listen any more than Lief would listen if told that, so instead he says,]

Then, if you feel that way, do better from here. If Haru is watching [as spirits in his world have watched Lief], then act in a way you believe would make her proud. So grieve, as I do not think she would have wanted you to kill yourself inside, and then—be the person she came to be friends with.