In a Tear Jerker sort of way Uda being the one to deliver the killing blow to the parasite that took over Nobuko's body because he felt that Shinichi shouldn't have to be the one to kill a creature that looks exactly like his mother is a heartwarming way of showing how genuinely decent Uda is as a person.
Despite what he lost, Shiro Kuramori made it clear he had no intention of killing Reiko Tamura’s baby. He did look like he was, but he did it to get a reaction from her. Before he died, he was asked by Hirama if his partner, Shinichi, was human or not, and he stated his partner was human who lost his family like he did. He took Shinichi’s secret of having Migi in his hand to the grave with him.
After Shiro dies, Hirama mourns his death by stating he was a good man.
Reiko Tamura protecting her baby from the police. Instead of allowing him to get hit, she uses her hair to shield him, calmly allowing herself to be riddled with bullets. When she knows she's seconds from death, she gives him to Shinchi, earnestly asking him to make sure her son is taken in and raised well by a loving human family; he agrees, and she dies with a faint smile. This shows how human she's become and how much she's changed since her earlier days on Earth, where her main concern was pondering why parasytes existed.
And in one of the stories in the Sequel SeriesNeo Parasyte, it is shown that Shinichi continues to check on and care for Reiko's orphaned son years later.
During the above scene, Kana's spirit wordlessly encourages Murano not to give up on Shinichi, despite all the danger he's going through. Though they competed in heartbreaking silence, they both just wanted Shinichi to be happy. While Kana's now dead, she can still make sure Shinichi is happy.
The anthology series Neo Parasyte offers plenty of these kind of moments:
In the story Migi's travels, it is shown that Migi is still alive and dreaming eight years after the end of the original story, while Shinichi and Satomi are Happily Married and have a son together.
One of the stories details the unlikely friendship between a human and a Parasite. Taking place 20 years after the main series, "The Telapathist and the Parasite" follows high school student Acchan as he is unnerved by the New Transfer Student Akira. After many of his classmates quickly believe him to be a Parasite, Acchan stops several of them from trying to cut some of his hair out to prove it. From there, Akira internally monologues about how several Parasites went into hiding following their public reveal, and that he was trying his best to understand and integrate with humans, and has learned more becoming friends with Acchan than from countless books and TV. While Akira has to expose himself to protect Acchan from an incoming truck and goes into hiding, Acchan realizes that, much like Kana, he can sense Parasites, and he's certain that even if his face changes, he'll be able to recognize Akira if they meet again, since that's how strong their friendship is.
"The Royal Prince" details the beginning of a human-Parasite bond in a similar vein to Shinichi and Migi between a young girl named Yuki and her Parasite "Prince". While the circumstances behind their initial meeting aren't ideal, Yuki being sedated in a mental hospital after witnessing the massacre of her family by a Stalker without a Crush, Prince ends up proving to be devoted to protecting Yuki and caring for her quickly after making himself known, even familiarizing himself with her Shoujo manga to develop a more "princely" persona. After having to witness her senpai be killed and discover that the killer of her family was her best friend's body with a Parasite, Prince reveals that he had taken over part of her brain that snapped following her finding her family, and offers to merge further with that part of her brain to let her better control her emotions and avoid a breakdown. While he tries to frame it as pragmatism so she doesn't shut down entirely, it's clear he truly cares about her, and seeing her tearful smile actually gets him to understand what a human's "heart throbbing" means.
The ending to "Secret Library". After saving her from a Parasite disguised as a cop, Arai convinces Hinako to hear him out and explains to her how he met his Parasite, Sally, after his dad nearly killed him, and the grief he feels due to blaming himself after Sally killed his father to save him. While Hinako is initially hesitant due to fearing Sally, she realizes that Arai is really just a good guy blaming himself for something out of his control while being a Stepford Smiler. So, out of gratitude for him saving her, she decides to make sure he can smile for real again some day, and the two become closer. The relationship between them can easily bring to mind the relationship between Shinichi and Murano, meaning it's not hard to see it as the beginning of a romance, but even then it's a sweet sight just for seeing Hinako so easily want to help Arai stop blaming himself after she had been so apprehensive of being near him out of fear of Sally.
