The Asahi has a piece (Japanese) on changes at the detention centres which house applicants for refugee status, overstayers and anyone else without a valid visa who comes to the attention of the authorities. There have been numerous accusations of abuse and detainees have held strikes to protest conditions. There might be an English version popping up later but it basically says they will provide some free legal consultation services and will also give advance notice of deportations. Currently, you get deported with no notice which can be shocking for anyone who is hoping to get approval to stay and may have family in Japan. In one recent case, this may have been the background to a death. The plan is to give two months notice so there is time to appeal or tidy up personal affairs. This applies to those who have posted bail and a guarantor, so there is some concern that anyone at large faced with a definite deportation might go underground.