This was a pretty cute slice of life piece. I enjoyed the first piece (Aquarium) very much, particularly because of the commentary of how stress in Japanese schooling can lead to serious consequences. I also really enjoyed the art associated with this one. The aquarium life is drawn beautifully.
The second piece (The Flying Stewardess) was the least appealing of the stories. I think this may be because I am American and I don't really feel the attraction toward the flight attendant business that it appears Japanese people do. It is still short and quick to get through, so it is certainly worth a shot.
The final story (The Heart is Your Kingdom) is an extremely cute story that covers a concept of long term love, long term crushes, and how things can get so complicated in high school in conjunction to them. It is very sweet and while it does feature a religious structure, it is in no way preachy.
Overall, Aquarium is a pretty quick read. The art is very pretty, even though it appears a little dated at times. The stories themselves are quick, enjoyable reads. They deal with concepts that are still very much relevant to high school students, no matter where they live. It was not the most exemplary of this sort of manga, but it was still enjoyable.