Once the Okinawa invasion started, Yahara recommended holding back Japanese forces for as long as possible and using them primarily in a defensive posture, rather than an aggressive one.

However, Chief of Staff of the Army, Lieutenant General Isamu Cho, soon became frustrated by the relative inaction of the battlefield, and recommended banzai charges at the Americans.

But when it was clear that Cho's samurai-charge methods were not working, but, rather, causing huge numbers of casualties among the Japanese infantry, along with loss of territory, Cho relented and allowed Yahara to continue to make tactical and operational decisions.

Yahara's method, since he did not have the firepower to fight the Americans directly in battle and knew that he could not possibly win, was to fight from caves as long as possible and then, once the caves were lost, to "retreat and defend"—time after time—until there was no longer any room to retreat to.

When Lieutenant General Cho and Lieutenant General Mitsuru Ushijima decided to commit ritualistic suicide in Mabuni caves, Yahara requested permission to commit seppuku alongside them, but Ushijima refused, telling him "If you die there will be no one left who knows the truth about the battle of Okinawa.

"[1] Cho instructed Yahara to make his way through the American lines to northern Okinawa and report to Tokyo on what had happened, and gave him 500 yen for the journey.

[2] After the two generals had committed suicide, Yahara hid with several other staff officers in a small cave whose entrance they had blocked with stone and waited for the opportunity to escape.

After hearing American troops drilling into the rock above them they relocated to another cave before deciding to split up.

He later joined a work detail before eventually three weeks after his escape from the 32nd Army headquarters his true identity was discovered by the U.S. military.

Following the end of the war Yahara was repatriated back home to Japan in January 1946.

32nd Army Headquarters soon formed (March 22, 1944) and assigned as Senior Staff Officer.