@Sweet_Seats there's a good way to write in magic and a bad way of writing in magic. This was the bad way of writing in magic. Her fat literally melted through her skin and then disappeared into thin air. There was absolutely no build up prior to this about her magical breathing being able to alter physical states. And I'm sure there's still physical rules in that world too. Even she didn't know it would happen.
"ITS MAGIC BRO" doesn't mean it makes sense plot wise. Also, the speed of which she "transformed" made the entire "fat girl" premise a ploy instead of plot. Not only is it offensive, it's also offensively bad writing.
Also, if her core personality was already rotten before getting weight and that personality was displaced by our transmigrated MC.... Why tf is the fat the "bad energy"??
If this many people think it's a bad chapter it probably is mate