Every year since its inception, the All-Japan contest has grown in popularity and stature. During that time, there have been many changes. Most notably, the half-size event, introduced in 2009, has become very popular. There are now so many entries that organising the event must meet new challenges each year.
For 2018, the contest in Japan will see some changes. The events will be renamed and there will be no preliminary contests. Consequently, the event will now run over two days rather than three.
Rather than just re-write all the changes here, I recommend that you check out the summary first hand at the NTF site:
Japanese: http://www.ntf.or.jp/mouse/micromouse2018/index.html
English: http://www.ntf.or.jp/mouse/micromouse2018/index_EN.html