I looked at that possibility, but Tokyo time is the same as Iwo Jima time so both places are in the same time zone.
I found a Japanese website which says the B-29s and P-51s were in the target area from 1108-1121 hours.
横須賀海軍航空隊大正5年4月1日開隊海軍で最も古く、敗戦まで存続した伝統ある航空隊である。教育・錬成を担当。各機種の航空戦技の研究、新型機の実用実験を担当。高…
"{U.S. 21st Bomber Corps/73rd Bomb Wing departs from Isley Airfield on Saipan Island B29: 114 aircraft, 7th Fighter Corps departs from Iwo Jima P51: Approximately 90 aircraft, first target at 1108-1121 (Nakajima aircraft, Musashino Manufacturing Plant), 94 missiles were thrown, 11 missiles were thrown at secondary targets, 2 missiles were thrown at opportunistic targets, and 7 aircraft were sortied with no effect."
This makes sense because the standard tour of operations for an Iwo |ima P-51 pilot was 15 VLR missions—about 105 hours flight time— plus whatever local ground support or patrols were required.
506th Fighter Group 457 Fighter Squadron 458 Fighter Squadron 462 Fighter Squadron Iwo to Japan are available area.
www.506thfightergroup.org
105 divide 15 is 7 so one entire mission is 7 hours meaning that flying from Iwo Jima to Tokyo would be 3 and a half hours roughly. This matches Ryniker's statement and the Japanese website because if they took off from 0800 hours and it takes about 3 and a half hours, then the reported time of 1108-1121 hours matches perfectly. This means that Christoe in his P-51 was shot down at 1130 hours rather than 1230 hours. It just doesn't make sense for him to enter Tokyo at 1108-1121 hours and get shot down one hour later.
As for the Yokosuka Kokutai diary saying that the N1K2s attacked the P-51s and B-29s at 0920 hours, the only thing I can think of is that the report meant 1020 hours which would be perfect.
As far I know this was the only mission which involed P-51s over Tokyo that day, so if the Yokosuka Kokutai says they encountered P-51s then they have to be the ones of VII Fighter Command that escorted B-29s of the 73rd Bomb Wing at 1108-1121 hours during which they lost Christoe and three other P-51s.