Tomioka waxaa loo magacaabay Ciidanka Xoogga Dalka Japan bishii Oktoobar 1940-kii isagoo ahaa Madaxa Qeybta Hawlgallada, wuxuuna sii waday inuu u adeego xilkaas labadii sano ee ugu horreysay Dagaalkii Baasifigga, xilligaas oo uu si guul darro ah uga soo horjeestay weerarkii Pearl Harbor. Wuxuu sidoo kale si adag uga soo horjeestay qorshaha Admiral Isoroku Yamamoto ee howlgalka Midway
, oo soo jeedineysa in Japan ay qabsato jasiiradaha muhiimka ah ee Fiji iyo Samoa halkii. Tomioka wuxuu sidoo kale ku riixay in diirada la saaro qabsashada Port Moresby ee New Guinea, ama sidii goob loogu soo duulo Australia, ama in laga saaro maraakiibta xambaara maraakiibta Mareykanka sida ugu macquulsan saldhigyadooda. Waxaa la diiday markii Yamamoto uu ku hanjabay inuu is casilo.