Takashina was born in Chiba Prefecture and was a graduate of the 25th class of the Imperial Japanese Army Academy in December 1913.

In July 1938, Takashina became commanding officer of the IJA 60th Infantry Regiment and was promoted to major general in March 1940.

Takashina was then assigned command of the IJA 29th division which was tasked with the defense of the Liaoyang area in Manchukuo, as part of the strategic reserve under direct control of the Kwantung Army.

Two days after the United States 3rd Marine Division landed on Guam, 25 July, Takashina planned a counterattack to push the Americans back into the sea.

His strategy was to gather up every available Japanese unit on the island and to make one huge offensive to flush the Americans out of their beachhead positions back into the sea.

Approximately six battalions were ready to attack the Americans by that time,[3] and the offensive occurred in the rain on the night of 25 July.