一も二も無く[ichimonimonaku] unhesitatingly
一言二言[hitokotofutakoto] a word or two
一石二鳥[issekinichou] killing two birds with one stone
一二に及ばず[ichininioyobazu] right away
一姫二太郎[ichihimenitarou] It's good to have a girl first and then a boy

うり二つ[urifutatsu] as alike as two melons (two peas in a pod)
黄道十二宮[koudoujuunikyuu] twelve signs of the zodiac
二度[futatabi] again
最小二乗法[saishounijouhou] least-squares method
三十二分音符[sanjuunibuonpu] 32nd note

伊佐木[isaki] chicken grunt (species of fish, Parapristipoma trilineatum)
一佐[issa] colonel (JSDF)
佐賀県[sagaken] Saga prefecture (Kyushu)
佐官[sakan] field officer
佐幕[sabaku] adherence to the shogunate

三佐[sansa] major (JSDF)
佐ける[tasukeru] to help
少佐[shousa] major
大佐[taisa] colonel
中佐[chuusa] lieutenant colonel