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.
Tear Jerker: At the end of the first volume, Ai insists on making sure Lizette is safe, even though the nearer they get to the demon world, the more the poisons in the area affect Ai. Lizette is unmoved at first, even planning to use the opportunity to kill her. Ai eventually collapses and begins to fade away, still wishing she and Lizette could be friends...and Lizette tells the other angels where to find Ai.