Tear Jerker: Night's death. It's just as emotional in the live-action drama, where Gaku is seen looking over the stored body of Night, wishing him "sweet dreams, 01" and leaving. The last shot is an ascending view of Night's body in the storage container, wearing his scarf.
Mika admitting that she was never Riiko's friend and stole guys Riiko liked because she could, then has Night's fanclub pelt her with mud and throws the friendship bracelet Riiko made her in her face. You just want to give the poor girl a hug.
They Wasted a Perfectly Good Plot: The story could have been alot deeper and most likely betterhad Riiko realized that everything she thought she wanted in a guy (in which she eagerly programmed into a figure) turned out to be not how she thought it would and rather chose the genuine, real guy who had always loved her and stood by her, rather than choosing a robot programmed to be a "perfect" guy. While Night is likable by any means and seems to eventually harbor genuine feelings for Riiko, it still makes her come off as rather shallow and even dumb. It's particularily grating in the scene where she chooses Night over Soshi, on the basis that "Night always protects me!" when 1. apparently she forgot the detail where she programmed him to do so, and 2. Soshi happened to be at the scenes, protecting her as well without her knowing, overall making her decision just seem unfair and poorly thought through. Then again, the mangaka did state that she didn't mean for the story to be deep, leaving the conclusion that it had a good chance to be so, but she either didn't realize it herself or simply didn't aim to write more than what it ended up as.
The Woobie: Riiko. Her parents are barely around, so she's very lonely beneath her goofy, cheery personality, she is in a permanent Slap-Slap-Kiss with Soshi, every guy she likes thinks she's a flat-chested weirdo, Mika was a False Friend who manipulated and undermined her because it made her feel better about herself and when she does get a boyfriend, he gets a fanclub who decide Night should be with one of them, not Riiko.