These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Good Bad Bugs: Koji and Claire in Quest Mode have to be leveled up separately. Even if you just decide to focus on one of the characters, he/she dies permanently just before the final boss. However, instead of spending hours leveling up the second character, you could just go to the room where the first character died and repeatedly kick his/her corpse. Since the body doesn't disappear, every individual hit counts as a kill worth a ton of experience. However, you don't actually gain the levels until you leave the room.