When Mei asks Kouichi how it feels to "not exist", he replies that although it's not that great, it took a load off his mind. Why? "Because now I know that you exist." Aww.
When Mei says that she prefer to have her eye hidden, just for Kouichi to say that her eye is beautiful. A small one but was very strong. She even left the place with a spring in her step.
Ms. Mikami taking a hit from Yukito who was trying to kill Mei. This in turn caused Kouichito punch Yukito. On the surface, it seems like he was simply defending his teacher and his friend. However, when we find out later on that Ms. Mikami is his aunt Reiko, it's a double whammy of heartwarming. The first is that the Reiko side of Mikami only knew Mei on screen in the beach episode, whilst she knew but didn't acknowledge her during Mei's term as the Non-Existent Student. Yet because she is her nephew's friend, she defends her regardless. The second whammy is that it justifies Kouichi flying off the handle and punching Yukito, because he was not only trying to kill Mei, but nearly killed his aunt in the process.
The entire montage of Episode 6 becomes heartwarming as Mei and Kouichi spend time together.
Episode 8, where the main cast from Class 3 go on a trip to the beach. It stands out because this is the first time in the series these group of kids actually get the opportunity to act like kids. This even gets a Lampshade Hanging in the episode itself where they breathe a sigh of relief when they realize they're able to make it outside of town safe.
