- Alas, Poor Scrappy: Mama Punpun spends her dying moments regretting not being a warmer mother to Punpun. This moved a lot of readers who had previously hated her.
- Alternate Character Interpretation:
- Punpun's mom. At times, she may seem to border Evil Matriarch levels. At times, she seems to just be grumpy. Besides Punpun, she is without a doubt the most conflicted character within the series.
- The ending leaves itself open for interpretation. Is it a happy ending because Punpun seems to be going down a path of normal and sanity now, or is he just a hollow shell who keeps marching on because he isn't even strong enough to kill himself? Word of God says the latter is closer to what he intended, but does state that he doesn't mind people interpreting the ending differently.
- Aiko gets a lot of this, particularly in later chapters. For example, whether or not many of her actions are an understandable effect of being a constant victim of abuse, or just plain and genuinely twisted and unforgivable, is a subject of debate. Punpun's own actions, which come from similar causes, are also debated frequently.
- Base-Breaking Character:
- Aiko. A lot of people dislike her due to Punpun's obsession with her severely screwing him up, making her the catalyst for a lot of his poor decisions and darker moments, even if she didn't want that to happen. However, some find her an incredibly tragic Woobie due to her past. Thus, Aiko gets a considerable amount of focus in fanworks despite her mixed reception.
- Punpun himself. While many fans of the story consider him a complex and well-realized character and empathize with him due to his horrible upbringing and obvious depression, the fact that he spends a lot of the story in a constant state of misery and self-loathing makes it difficult for a lot of people to get behind him. In addition to this, as the story goes on his character development turns him into a gradually more unpleasant and horrible person, which only makes him more contentious.
- Darkness-Induced Audience Apathy: Has been known to happen. The story eventually becomes so depressing and uncomfortable that it can turn people off. In particular some people feel that Punpun, initially a sympathetic if very flawed Classical Anti-Hero, gradually becomes such a horrendous individual that they find it hard to excuse his behavior or care what becomes of him. In a post-series interview, Asano admitted that he had a somewhat antagonistic relationship with the readers, and that sales took a sharp decline every time something really dark or upsetting happened. He's said this is why he took a lighter and less nihilistic approach (at least by Punpun standards) in his later work.
- Diabolus ex Machina: Some people that a number of the twists in volumes 12 and 13 pertaining to Punpun and Aiko are this.
- Ho Yay:
- The end page of chapter 104 depicts Aiko and Sachi cuddling together.
- Seki and Shimizu have a very strong relationship as a result of the former saving the latter's life from a fire (which results with both holding hands and Seki looking embarrassedly to the side). They are the only friends from the group to remain close throughout their teenage years, keeping each other grounded. Seki's girlfriend once asked if he was gay from how much he talked about Shimizu.
- Squick: In chapter 137, Punpun and Aiko have sex in a forest. And right after a very disturbing emotional confrontation between the two of them, at that.
- Trapped by Mountain Lions: Many people who read the story and who otherwise have very positive opinions frequently criticize the Pegasus Cult subplot as being confusing and question what point it serves in the story, when they're primarily interested in Punpun's life and Character Development. In an interview Asano later clarified that Pegasus and his followers actually WERE battling evil and saving the world, but many readers didn't find this to be sufficiently clear in the manga and still find it to be the weakest part of the manga. The cult's quest for spiritual upliftment is functionally unrelated to Punpun's personal struggles, so it could just as well be excised from the manga without detracting from the story.
- True Art Is Angsty: The manga is frequently held in high regard by people who read it, considering it a masterfully done Coming-of-Age Story, and it is frequently praised for its lifelike characters, strong art, and skillful visual storytelling. It's also relentlessly dark, cynical, and sometimes even nihilistic.
- What Do You Mean, It Wasn't Made on Drugs?: Characters include a god of poop in an alien spaceship, a perpetually smiling, photorealistic god with an afro◊, and the main character and his family are usually depicted as cartoony birds, despite everyone else in the series being relatively very realistically drawn, and at one point Punpun turns into a triangle for a while, when he starts living alone. The surrealism gets toned down as the story goes on, however.
- The Woobie: Aiko. She had the most horrible life of anyone in the story by a wide margin. She desperately yearns for the comfort and warmth her cold, abusive mother never showed her. This desire goes unfulfilled.
YMMV / Goodnight Punpun