The 24th Infantry Regiment was the only full strength Regiment of the 12 Regiments in Japan during the occupation of Japan. with a full compliment of 3 battalions.
There were four Divisions - ie 12 Infantry Regiments - in Japan during the occupation and on June 25th when the Korean war began. All Regiments were under strength with only two battalions except for the 24th Infantry Regiment. All battalions were under-strength and had an imcomplete TO&E.
Most of there equipment was outdated, inoperable or very poorly maintained.
Oops, the 19th and 34th were part of the 24th Infantry Division not the 25th Inf. Div. Other than that what I said is correct. The 24th Infantry Regiment was disbanded by October 1951 long after troubles in March of 1951 when the 8th Army began the spring offensive across the Han river had been detected.