Does anybody bother with Emi?
Yes, she's a super lewd Darkness kind of girl, and bringing her along to make her suffer is lots of fun. Once she died a hundred times (+2000 HP) she's an absolute maso tank that doesn't need any ability to guard her pals, like the ability guard stuff. She's just based like that. Then you H her, she's back to level 1 but still has her +2000 HP, so who cares about levels? Just make sure to feed her some more HP special itenz. Bitch is absolutely badass. You can bring her along "suspended" already with nothing ever to do (so she doesn't take any turns or anything), maybe put healer in the back and you're golden.
Seems kind of a pain in the ass to farm her deaths.
Nah, it's super easy if you do it all in Crane's hideout. Step 1: get Crane. Step 2: use Crane to get Emi easily. Then just redo Crane's hideout mission with Rance and Emi. Skip intro, run into red battle event. Let the goblins have their way with Emi, finish battle super quick once she ded, or if mission timed out. Abandon. Repeat. Goes super fast, and even once she has already most HP, you just might need a second battle to kill her. I did it, and so can you. Just keep the plot in the back of your mind, just you and Emi going on adventures to have some monsters have their way with her. Exciting. And in the end it's totally worth it.
Coincidentally Crane's hideout is the perfect dungeon to level up and get super rich at this point. Just get in, do a battle or two using all the badass stuff and abandon after two or three battles. Keep experience and gold. Repeat.
Similarly it's also nice to go on chest hunt in there, especially if you've got Tomato already. She a cute, playing mimicry and stuff. Chests all over the place.