He served at several land bases around Japan (including Ōmura and Saiki Air Groups on Kyushu) before he was assigned to the carrier Akagi in May 1939.

On 7 December 1941, he participated in the Attack on Pearl Harbor, where he led one of the Zuikaku dive bomber divisions that bombed and strafed American aircraft and hangars on Wheeler Field.

In April 1942, he participated in the Indian Ocean Raid, where he led one of the Zuikaku dive bomber divisions that bombed and sank the British carrier Hermes.

[1][2][3] Meanwhile, the actual USN carrier fleet was spotted and Rear Admiral Chūichi Hara planned to launch an afternoon strike as soon as Takahashi's force returned.

The strike was ill-fated as it missed the USN carriers due to poor weather, and in return lost eight Nakajima B5N torpedo bombers and one D3A to radar-guided interception force of Grumman F4F Wildcat fighters led by Lieutenant Commanders Paul Ramsey and James Flatley.

His group temporarily moved to Buin airfield to participate in Operation SE and were sent to attack the Allied shipping around Guadalcanal.

Due to a leaking fuel tank, he made an emergency stop at Vella Lavella before he returned back to Buin and subsequently to Rabaul.

[1] Ema survived the war and later published a book that comprises a collection of battle accounts from several IJN dive bomber aircrew, including himself, Sadamu Takahashi, Keiichi Arima and Zenji Abe.