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

亜麻仁[amani] flaxseed
亜麻仁油[amaniyu] linseed oil
杏仁[kyounin] apricot seed
一視同仁[isshidoujin] loving every human being with impartiality
核仁[kakujin] nuclear bonding

親仁[oyaji] one's father
仁愛[jinai] benevolence
仁王門[nioumon] Deva gate
仁王力[niouriki] Herculean strength

メディア王[mediaou] media mogul
愛染妙王[aizenmyouou] Ragaraja
烏芻沙摩妙王[ususamamyouou] Ususama Vidya-raja
王位[oui] the throne
王化[ouka] imperial influence

王家[ouke] royal family
王冠[oukan] crown
王宮[oukyuu] royal palace
王権[ouken] royalty
王国[oukoku] kingdom

一門[ichimon] family
陰門[inmon] (female) genitalia
開門[kaimon] opening gate
凱旋門[gaisenmon] arch of triumph
冠木門[kabukimon] gate with a crossbar

関門[kanmon] barrier
玉門[gyokumon] beautifully decorated gate (euph. for female genitalia)
桑門[soumon] monk
軍門[gunmon] camp gate