tl;dr: A short manga with a pretty generic take on bullying with a reasonably well told mystery attached to it.
This manga has two major facets, both of which are decent, but both of which also feel like they’re somewhat lacking. In a very broad sense, the manga is about the protagonist, Matsuda, feeling a sense of guilt after something terrible happens which he feels is a result of him merely looking away from bullying that was occurring around him. At this point he feels a responsibility to help the victim of bullying, Wakatsuki, but it’s already too late and Matsuda needs to deal with that. The manga explores the feelings and roles of various characters that are affected by the bullying and its aftermath, though ultimately only three are properly focused on. I think focusing on a small number of characters makes sense as this is such a short manga, but even with that it still didn’t feel like it spent enough time on them. It does enough to get you to care about the characters, but it didn’t really feel like it fleshed them out enough. Ultimately, even though it built up the foundation to be quite a bit more, it felt pretty superficial and it didn’t really seem to say anything beyond the standard bullying is bad, has wide effects, and you should step in and stop it before it’s too late. Thus, it felt like a lot of wasted potential.
In addition to that, there’s also a mystery that pops up, though it doesn’t become apparent until well into the manga and after a lot of what will be important clues have already been revealed. The mystery is pretty simple, but it’s still interesting to watch as it’s unraveled. It was interesting to see how the various characters fit into it and see what earlier seemed like minor details pop up in a new context with major importance. There were some incredibly forced elements that were pushed into it in order to make the plot work, such as the protagonist just happening to have a sister that’s married to a high-ranking police officer that can provide him with secret information or the protagonist just happening to have some supernatural veranda where random things like newspapers from the future pop up, but even with them the mystery felt pretty well written. The ending too was well written and fit the manga perfectly, but at the same time I absolutely hate it and wasn’t satisfied with it in the slightest. The art is decently solid and works well enough for conveying what it has to.