Though I never read the Japanese book from which this movie is based - I thought the comments of other posters missed a salient point in their reviews.
No one brought up the exploration of the focus on the "pure and perfect" order of things that is a backdrop for the exploration of the boys in the film. I'm assuming that that refers to the idea that there is such a thing and that when we deviate from it - meaning is somehow bastardized - and focus and purpose are lost. Unfortunately, when - during exploration - one destroys the object of one's investigation that too seems a bastardization of the "pure and perfect order."
A disturbing film but I do like Kris Kristofferson and he did write the music for the soundtrack which is beautiful. I tried many times to find a CD of the soundtrack but the movie has been out of print for so long that it is probably not possible to find one.