Definitely not a sure-fire hit for anyone who wants fluffy, happy-ending stories.
Admittedly the first story got to me, because it's not an ending I wanted, and even though it was realistic and fair, it made me sad.
It's a downer to see your favorite character as the most depressed in the ending, ya know? I genuinely liked him better than both the original MCs in this story, and the MC crushing his feelings was a kick to the gut. While I can appreciate the mangaka's boldness to be realistic and original, I don't like that disappointed feeling. If it had truly just been about the two MCs, I'd be happier with it - they were clearly not meant to be a couple (straight vs. gay, for one thing), and I didn't see romantic chemistry between them, so I wouldn't mind if they were the only ones feeling a little let-down by the experience. But I felt genuine sympathy for the unfortunate 'third wheel', and I was hoping he wouldn't be screwed over, and yet.. he was. I saw it coming, but I hoped it wouldn't.
Hope didn't work, and I still got an ending that let me down. The characters all made a full circle, and yet left the situation with the exact same grievances and problems they had before it all started. No positive progress; no change for the better, except a subtle realization about friendship in there.
It's difficult to read a story with a line like, "The world won't let me be with anyone. The world won't let me have ties to anyone," and realize, at the very end, that the mangaka did nothing to improve that character's situation. But it's no use being mad at the story, because it's well-written, it just feels unnaturally cold.
Regarding the second story, it succeeds at being less depressing and more uplifting (depending on how you interpret it), but it feels oddly flat compared to the first. Maybe because of its shorter length, the characters feel less fleshed-out, and the story isn't as engaging. This one's along the lines of a typical 'fluffy' story, but it's also very 'slice of life' in that there's no major plot going on. It's easy to read this when half-awake, and forget everything the characters said. It lacks the kind of punch (for better or worse) that the first had, and feels less developed in comparison.
The third story is immediately engaging, as it follows a female protagonist. I have to give credit where it's due, this mangaka has some original ideas. The dynamic between her and the boy (won't say who, to avoid spoilers here) is very intriguing. I really enjoyed this, it's a nice change of pace. And I have to say this story, even though the ending felt predictable by now, was very touching and sweet. In its own way, it has a lot of heart, and it didn't make me want to cry while still managing to have a sorrowful impact mixed with all the good. The protagonist's point of view added a pleasant spin to the events.
The fourth story has an interesting format, being told in short snippets (using a multiple perspective, much like a quicker version of the first story's mechanic). It keeps things interesting with little details about each character. However, with a variety of new names and some look-alike faces, by the time it arrives at the fourth character I found myself getting confused as to who they were. The art is nice, but sometimes the different faces resemble each other, and many of the guys have similar hairstyles. So unless you're really sharp with names, a story like this can get confusing to follow. The ending is touching in a way, but I lacked an emotional connection with the characters (too many of them, and too little time with them) to feel the full intended impact.
The fifth story mixes things up a bit. It's immediately more gritty from the start, with older characters that are drawn in a much more serious, detailed style. Unfortunately, I didn't care for the characters themselves. They seem realistic as always in this book, but they lack appealing qualities - they seem wrapped up in being antagonistic to each other, and the criminal underworld they live in didn't capture my attention either. By its end, the dialogue started to blur together, and again I feel I missed the full impact of the ending.
Story six (wow, a lot of stories in this book!) is a kind of tag-on to the first story. It's done in a much more comical fashion, however, it does make the canon more optimistic of an ending, if you choose to take it seriously. But it's almost so silly that it disrupts the powerful emotional setting of the first story, so it feels like a guest artist came in and did a quick fanfiction about it. Useful for an amusing gag, but empty and flat (and still open-ended) as a 'sequel'.
Story seven appears to be a similarly humorous add-on to story three, but its light-hearted tone fits it much better, since that original chapter was more uplifting and hopeful to begin with. It's short, but very cute.
Story eight is... an add-on to story five? To be honest I can't tell... It's very very short anyway, and the last and final of the short 'gag' sequels. But again, it adds a positive spin to the ending, if you were left wishing for one.
All in all, this book is a mixed bag for me. The first story is extraordinarily powerful, but left me disappointed and feeling that it was unresolved at the end, but beautifully so. If you can stomach some of that sadness, it's a very well-written, engaging read. The following stories have their good and bad points, but none shine so strongly as the title piece. I believe I would've rather read a book with only two powerful stories, instead of one strong work and a few that were less impactful. But this all comes down to personal preference. Either way, I hope this long review (I apologize for rambling forever, lol) is helpful.