The limit does not apply to Flet's ADSL users, rather to other users of Flet's. I believe they offer 12mbps FTTH connections. Things are supposed to be limited starting o­n the 23rd.
This restriction o­nly applies to upload; download traffic does not count towards the daily limit.

Internet Initiative Japan will begin limiting upload traffic for their ISP customers o­n the "IIJ4U" service o­n the 23rd. The corresponding users will be informed by email from IIJ. Download traffic does not apply to this limit.

The services being limited this time around are the "Flet's Connection Option" and "Access Comufa (community fiber?) Option," both of which will have a 15GB/day upload limit placed o­n them. While users will be notified by email, IIJ has said, "users who have particularly high traffic will have the limitation placed upon them immediately."

Since Flet's ADSL has a maximum upload traffic of 1Mbps, it it not affected by this limitation. However, "In the event that Flet's ADSL traffic increases, there could be limitations imposed upon them too."

IIJ points out that, "some users of the Flet's service whose upload traffic varies greatly from the average, hog the network hardware." The result is, "many users are affected by lower transmission speeds, poor communication signals, etc. and suffer bad performance," so, "in order to correct the inequality amongst the users, we are introducing this generic rule." Rather than naming a particular concrete application name such as WinMX or Winny, IIJ has simply said "rather than limiting specific file sharing applications, upload traffic of users will be limited to 15GB per 24 hour period."

Inspired by:
http://internet.watch.impress.co.jp/cda/news/2004/02/09/2044.html

About:
http://www.iij4u.or.jp/info/20040209-1.html