One of a favorite animes ever.
Story : Long story short, it's about a guy who can see a girl who died and about how him and his friends from childhood deal with it. There's a love triangle of some sort which really reminds me of Nagi no Asukara (watch both, you'll see what I mean). They are trying to figure why this guy can see her and why she's there, and how to fulfill a wish of hers(which she can't remember). It doesn't sound all that interesting when you read it like this, but the anime brings it to life and it's just amazingggggg. It's a decent and simple plot for a short anime like this. Menma's death really affects all the characters a lot. It's weird because it happened when they were kids. The characters still make the death affect them in high school.
Art : The art is nice, although nothing special. Wish Menma looked older and not so kiddy, but it fits her character.
Sound : The OP is good, but the ED is amazing. It fills me with feels every time I hear it.
Character : Character development was just so amazing. You get to see all the characters grow and overcome their personal obstacles. Although, Poppo wasn't nearly as developed as the rest of the cast, though. I wish Menma could've been more grown up physically and mentally.
Enjoyment : I'm glad that it was short as nothing was filler. Every episode really progressed the story. It was so emotional. I'm really not the type to cry or anything, but I did tear up. The feels. The most heart wrenching series I've ever seen. But you can tell they purposefully did it that way just to make you cry.
Overall : I'm so happy I gave this a chance. My friend recommended it to me. I heard of it before, but it didn't sound appealing. If you feel this way, watch it. Just watch it. You won't regret it.