Since this is a collection of one-shots, I'll review them one by one.

Chapter 1 - "Musume-iri Hako" (Girl in a box): 6

Quite a generic story, similar to the premise of Hinamatsuri. An alien girl is dropped on Earth, and a delinquent finds her and takes her in. It is a one-shot, so the story isn't anything amazing, but the comedy is pretty good and the art style is interesting.

Chapter 2 - "RKD-EK9": 8

Great story, great art, and edgy characters. The story and the theme are pretty unique, with scientists proving the existence of "Heaven" and trying to get there. Strong recommend.

Chapter 3 - " Nani made nara Koroseru?" (What can you kill?): 8

Crazy girl and apathetic boy. Murder story. The art was breathtaking at times, I loved it, and the story was pretty captivating as well. It would have been infinitely better with a little backstory, at least, and a longer length (it only has 18 pages), but it is still very satisfying for a one-shot.

Chapter 5 - "Koi Aru Douguya" : 7

Quite delightful art, and a quite engrossing story: it is about a delinquent that falls in love with a good girl. Wandering in a bizarre shop owned by a demon, he buys a special ring, which, if put on your crush's finger, is supposed to make them fall in love with you. And, well… the rest of the story is for you to find out! You won't regret it, although it is not as original as other one-shots on this list.

Chapter 6 - " Off-side wo Oshiete" (Teach Me the Off-side): 6

Frankly, I started reading this volume because of this one-shot, which is the work of Nakayama Atsushi. Obviously, the art is as amazing, as always, but sadly, that's about it. The story is about a 3rd-year high school boy teaching a (girl) freshman about the off-side rule in football. Never have been one to especially like the sports genre, it was quite boring for me, but if it's your cup of tea then by all means give it a try.

Chapter 7 - "Doushitemo Kanaetai Tatta Hitotsu no Negai to Wari to Sou demo Nai 99 no Negai" : 7

Long title, damn it. I was really surprised to find a Juuni Taisen chapter here; who would have thought? I enjoyed it, and if my memory serves me right, this is also in the anime. If you're not a fan it may confuse you, but I think it would still be enjoyable.

Chapter 8 - "Bokura wa Zatsu ni wa Manabanai" : 8

Very interesting story and characters, and the art was okay. Two high-school students, a quirky upperclassman and "his assistant", an underclassman (who was mostly dragged into this), go on a trip to Africa to find out if the sweat of hippos is pink. Truthfully, it was really entertaining.

Overall, I'd say this is a pretty good manga, and it also takes almost no time at all to read, so give it a try. I didn't find chapters 4 and 9 yet, though, so if you do, tell me.