Misawa AFB 7th Fighter Bomber Squadron USAF pilot Second lieutenant James Henry Petty was flying a F-80C jet fighter in a slight turn to the left at 25,000' 320 mph, heading northeast about 45° azimuth to meet up with a lead aircraft, apparently another F-80C, piloted by Lieutenant Sofbom of 7th Fighter Bomber Squadron also heading northeast at 45°.
At this point in a sharper gradual left turn, when he saw an UFO about 3 miles away at his 2 O'clock position about eastnortheast following the lead aircraft in a tracking position about 1,000' below and to the right rear, about 5 O'clock position roughly 1 mile away, from the lead aircraft traveling about 275 to 300 mph, silhouetted against clouds.
During the lead aircrafts wide left turn that eventually resulted in a 260° heading, the UFO accelerated and pulled up to level position, at 3 O'clock, and climbed to the lead planes altitude while the F-80C rapidly approached and overflew both the lead aircraft and UFO, having to climb slightly to avoid collision.
Now heading about northwest about 315°, but getting a very good look from the top and both sides of the UFO.
Petty saw that it was a rectangular cream colored flat object appearing to be made of musli” about 20' high, 60' long, but only about 2" thick, oriented vertically, not reflecting sunlight despite bright Sun.
No exhaust, no apparent means of propulsion, not wavering or fluttering.
Petty first thought it was an aerial tow target but knew there was no aerial gunnery scheduled.
After being overflown, UFO pulled away from lead aircraft, accelerated to 600 mph on a 330° heading, climbed to 28,000 ', overtook and crossed in front of Petty's F-80C from behind and left to right, from about Petty's 7 O'clock to 1 O'clock positions, and disappeared in the distance against a clear sky.
Similar incident next day near Wakkanai.