Re-signed for another contract but potentially want to leave before contract start

Hi everyone. This is my first year in Japan, so I'm still getting used to some of the contract terms here.
I started teaching here back in April. The school I work for was decent, but quite far from where I wanted to be initially. I ultimately decided to take it because it was at one location and they gave six weeks of paid vacation a year (a perk that's not easy to turn down). I signed another contract with the same school, but there are some changes for next year, one of which may be losing that vacation time.

My current contract ends at the end of March and then I would start a three year contract in April. My question is what are my options when it comes to leaving? Some of the things I've read online suggest I need to work a full year of that new contract before quitting, but others say giving a two week notice is all that's required legally. My employee handbook states they would like a three month notice. I am fine with giving this to them so they have the chance to find a new teacher. Will I be required to work the full year of the next contract before I give notice?