another classic movie info request

[chiefdog]

I am looking intensly for an anime i saw on Sci-Fi channel in like '98.
This anime was about a school kids that are preparing for a festival or something and all of a sudden everybody else disappears except for these certain characters. It ends up getting very trippy and existential, something about cryo pods and mysticism(paper demon barriers) Oh and they get their hands on a big tank.

I know this description is kinda all over the place but this is all i remember. I hope that someone remembers the name of this one it was very interesting and kept me up late night. too bad i forgot everything the next morning. peace and thanks for anyone that helps out.
~Travis