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

偉才[isai] genius
何才[nansai] how old?
画才[gasai] artistic talent
鬼才[kisai] wizard
賢才[kensai] man of ability

口才[kousai] clever speech
才覚[saikaku] ready wit
才学[saigaku] talent and education
才幹[saikan] ability
才器[saiki] talent

隣の芝生は青い[tonarinoshibafuhaaoi] the grass is always greener on the other side
燕青拳[enseiken] Yangqingquan
青竜蝦[shako] mantis shrimp (any marine crustacean of order Stomatopoda, esp. the species Oratosquilla oratoria)
灰青色[haiseishoku] grayish blue
紺青[konjou] navy blue

青眼[seigan] aiming at the eye (with a sword)
青い[aoi] blue
青い鳥[aoitori] bluebird (Sialia spp.)
青褪める[aozameru] to become pale