I suppose it depends on what you consider to be a "happy ending", but I personally would be disappointed if the ending is a simple " Years have now passed and I'm a better person now, glad I now have a family of my own and live happy and didn't ruin anyone else's life in the process" <-- That sounds shit, and that is technically a "happy ending".I repeat what I said a few months ago, I at least expect something happy in this true ending, I just want something minimally happy to make it worth it, because if it's a sad or poorly written ending I will genuinely be disappointed as hell with Lil.
Now I know you said minimally happy, but the only real outcome that I would consider a happy ending, is one where the girls get over Akira and realize he really is a shit guy; which to be fair, he has acknowledged many times and not just out of self deprecation. Though even if there is an ending where Akira can overcome all of his shit side and at least die in peace with the fact that he accepts what he is and what he has done, I'd be all right with that, a part of me thinks he has been dead all along to be honest.