That is what I would like to know kqcke for you. Whether Japan is going to follow the Wests example and reduce the number of fighters in their fleet or start to design a new fighter or another thing would be is to buy more GCAP/Tempest's or to replace the F-15Js which are getting rather old.
2nd Air Wing (Chitose)
201SQ (F-15J)
203SQ (F-15J)
3rd Air Wing (Misawa)
301SQ (F-4EJ→F-35A)
302SQ (F-4EJ→F-35A)
6th Air Wing (Komatsu)
303SQ (F-15J→F-35A)
306SQ (F-15J)
7th Air Wing (Hyakuri)
3SQ (F-2A)
8th Air Wing (Tsuiki)
6SQ (F-2A)
8SQ (F-2A)
5th Air Wing (Nyutabaru)
305SQ (F-15J)
202SQ (F-35B)
9th Air Wing (Naha)
204SQ (F-15J)
304SQ (F-15J)
As of March 2025, the JASDF fighter fleet looks roughly like this.
Japan’s planned F-35 procurement consists of 105 F-35A and 42 F-35B.
With a standard F-35 squadron strength of 21 aircraft (4x flights, CO, XO, and 3x reserve), this allows for the formation of 5 F-35A squadrons and 2 F-35B squadrons.
The F-35A is being introduced now to the 303rd Squadron, while the F-35B is being introduced to the newly established 202nd Squadron.
It has been reported that the F-35A will soon be deployed to the 306th Squadron at Komatsu Air Base, and that from 2031 onward, one of the F-15J squadrons at Chitose Air Base is planned to become the fifth F-35A squadron.
Because aircraft of the same type are often stationed at the same base for maintenance and logistical efficiency, the 305th Squadron at Nyutabaru will most likely become the second F-35B squadron.
The JSI upgrade will be applied to 68 F-15J belonging to the remaining three F-15J squadrons. The originally cited figure of 98 aircraft included 30 F-15DJ, but it was probably judged too costly to assign such upgraded aircraft to aggressor units (which operate around ten or more F-15DJ) and other roles.
The F-2A squadrons will, of course, be replaced by GCAP from 2035 onward.
To answer the question directly: yes. The F-15J is expected to begin retiring from service next year, with the airframes slated to be used for spare parts or scrapped.
However, the number of JASDF fighter aircraft is set to increase. According to a plan announced in 2022, the fighter fleet is scheduled to grow from the current 290 aircraft to 320 “by around ten years from now.” Details of how this increase will be achieved have not yet been made public.
Flight Global reported back in July that the number of F-15Js slated for upgrade has been cut to 54. Unfortunately, this figure has kept shrinking over time: the original plan called for 98, then it dropped to 68, and now it stands at only 54. It seems that just two (?) JASDF squadrons will operate the F-15JSI.
https://www.flightglobal.com/fixed-...umber-of-f-15js-to-be-upgraded/163789.article
What is the source of that number?
At least within Japan, the commonly accepted understanding remains that 68 aircraft will undergo the upgrade.