Full marathon total participants are capped at 12,000 runners and half-marathon (plus the HM for wheelchair) is at 5,000.
However, it is a first-come, first-serve basis so do register early if you want to join the marathon.
For more details, head to :
English site: http://chiba-aqualine-marathon.com/2016/en)
and also, some of the running information sites : http://marathons.ahotu.com/event/chiba-aqualine-marathon-half-marathon-wheelchair-half#event
Maybe I'll see you there too? ;-)