Metamorphosis, otherwise known as Emergence, in my opinion, is a pretty terrible manga. I'm not here to kink shame or anything, and I know that this is hentai and it had to have scenes as it did because of that, but the way the terrible situations were depicted so sexually was extremely disgusting. You'd have to have something wrong with you to find that hot, sorry. The only reason I'm rating this as high as a 5 is because throughout the manga I did somewhat get attached to the main character, Saki. Despite being bland, I continuously felt bad for her.
*MAJOR SPOILERS FOR ENDING
Another reason I'm rating it as high as a five is because of the ending. No, not because of the completely unrealistic scene where a group of teenage students continuously kick and sexually harass a pregnant lady until she's bleeding and on the brink of death. But because of the bathroom scene. That scene had me in tears, and I didn't even like the manga. And when she put her glasses on and looked at her reflection... I just couldn't.
Overall an unrealistic and quite gross manga, however, it succeeds in making you feel emotion and sympathy for the main character.
SIDE NOTE: I know a large majority of manga are unrealistic, but I only commented negatively on the fact that this manga is unrealistic due to the overwhelming amount of people saying stuff like "omg it's so scarring and disturbing because it's so realistic!!!" is pretty stupid. I get that it's realistic in the sense that yes, many teenage girls and boys are reeled into using drugs and their lives are ultimately ruined, but I feel the manga just took that and used unrealistic shock value to draw in readers.