This is like your mostly typical, relatable slice-of-life anime with a lot of unique ideas and execution, with charming and charismatic characters that all are cool, and at least, decent when they're around.
The most unique thing I've noticed about this anime is its animation: 
The chibi-style animation combined with some other visual effects makes this a visually pleasing anime, and with its quite slow but effective pacing, it works.
Pine Jam did an excellent job in the animation department, although it could be KINDA rough in episode 10-onwards, I love it every time when Nagisa is pouting or the entire anime just turn off all the colors, it just makes everything all the more funnier.
The characters are good, but has some problems: 
Let's start with Nagisa, now she's a quite creative character, with a lot of ways of spoiling Junta, along with being quite likeable, while not EVERY single prank that she does is "funny", they still leave a passionate and relaxing feeling in your heart. She's a bit of a cuchurrumin though.
What i DON'T like about Nagisa (and this sometimes get extended with other characters), is HOW MUCH SHE MENTIONS JUNTA, this honestly what's bugging me out the most since every episode, she at least mentions him like 50 times, I even speculated that Junta committed crimes and assassinated her family all because of how many times SHE mentions him, and while I do get that it's for the purpose of Junta getting recognition, it still is very annoying.
Next is Junta, he is also quite unique, because of his inner "invisibility", not ACTUALLY invisible (people can still sense him when he is touched, or a loud sound he makes could alert the entire class), just that, everyone overlooks him, and that is all changed when Nagisa shows up. For me, I believe his personality is at its best when he's with Nagisa or with anybody relating to Nagisa.
When he's alone, he's quite boring, and not as interesting, as he still has a quite generic personality, luckily, these moments are quite few and far between.
For Akina? she is SOMEWHAT perverted to Junta, prevalent in episode 8, but that doesn't steal her character away or anything, she does help Nagisa, especially her cooking and ability of making meals, and that's really all her character
Seita is introduced a bit later into the story, he's quite a wingman to behold, he even has Nagisa as her friend.
The story is simple, and it can get entertaining:
It's a simple enough story that doesn't feel brainless, yet executed pretty well, and while it CAN be repetitive, it still is fun seeing the adventures and places the characters go to.
The pacing is quite slow, but flows at a natural pace.
Overall, a pretty good anime, if you can get over the constant mentioning of Junta, you'll have a good time seeing the bittersweet and sheer wholesomeness that this anime delivers.