How do Japanese school rankings work?

Through experience I've noticed that school ranking is slightly signifigant. Such as wanting to go to the highest ranked school for your area and such.I'm trying to find out what the best and worst ranked high school is in Tsuchiura, Ibaraki prefecture. On the website I'm on that specializes in school ranking, they don't give the specific area, Tsuchiura, but instead the whole prefecture , Ibaraki. Why is this?, also how can someone find out what the best school in their specific area is?
Many thanks :)

Lots of missing information here... If you're talking about high schools, and your goal is to enter a good university, then each high school publishes on its website detailed statistics about which universities its graduates entered.

It's probably because students are not restricted to going to schools in their city, and instead look prefecture-wide (and sometimes into neighboring prefectures if the commute is reasonable) to find a school that fits their criteria. Afterall, Tsuchiura only has 9 high schools in the city, which doesn't provide a very useful set of rankings since they basically have one school in each rank class.

Btw, did you find this page? If you want to you can figure out the Tsuchiura specific rankings from that, but to you can also pretty much figure out the rankings based on the high school names themselves.

http://xn--swqwd788bm2jy17d.net/ibaraki.php

The link that yllwsmrf provided is a ranking of schools according to their hensachi. Hensachi is a sort of a score that cram schools mainly use to measure the applicants-to-be's achievements.

It doesn't necessarily mean that the schools with higher hensachi is the "best/worst" in every way. Hensachi is only about scores for entrance exams.

Some schools with lower hensachi may have a better reputation for their unique education or for their history or for sending graduates to better universities and jobs.

Some schools may be easy to enter (with low hensachi) but gets tougher once you get in, or vice versa.

By knowing your school's hensachi, you can predict the level of freshmen they will be accepting, but that doesn't necessarily mean that the older students and graduates are in the same level.