- jō o kojiakeru (錠をこじ開ける): to pick a lock
- kofun (古墳): an old tomb, a tumulus
- kofunjidai (古墳時代): the tumulus period
- kofūna (古風な): old-fashioned, antiquated
- kogai de (戸外で): in the open air, out of doors
- kogai no (子飼いの): kept from young, reared from young
- kogai no (戸外の): outdoor ~, open-air ~
- kogaisha (子会社): a subsidiary firm, an affiliated company
- kogane (黄金): gold
- kogane (小金): a sizable sum of money
- koganeiro no (黄金色の): golden
- koganemushi (黄金虫): a goldbug
- kogara no (小柄の): small, of small stature
- kogarashi (凩/木枯し): a cold wintry wind
- kogareru (焦がれる): to yearn for, to long for; to be deeply in love
- kogasu (焦がす): to burn, to scorch, [毛を] to singe, to char
- kogata no (小型の): small, smallish, small-sized, miniature, pocket, pocket-size
- kogatajidōsha (小型自動車): a midget car
- kogatana (小刀): a knife, a pocketknife, a penknife
- kogatka suru (小型化する): to miniaturize
- kogecha (焦茶): dark brown, a dark brown colour
- kogekusai (焦げ臭い): to have/give a burning smell; to smell something burning
- kogeru (焦げる): to burn, to be scorched/charred/burned
- kogetsuku (焦げ付く): to burn and stick; [貸金が] to become uncollectable
- kogireina (小綺麗な): neat, trim, tidy
- kogitsukeru (漕ぎ着ける): [船を] to row up to, to manage, to contrive
- kogitte (小切手): a check/cheque
- kogitte de harau (小切手で払う): to pay by check
- kogitte o furidasu/kaku (小切手を振り出す/書く): to draw a check
- kogittechō (小切手帳): a checkbook
- kogo (古語): an archaic word
- kogoe (小声): a low voice, a whisper
- kogoeru (凍える): to freeze, to be numbed with cold, to become numb with cold
- kogoraseru (凍らせる): to freeze, to congeal
- kogoroshi (子殺し): infanticide, an infanticide
- kogoto (小言): scolding, a rebuke, fault-finding, complaint
- kogoto o iu (小言を言う): to scold, to find fault, to complain, to grumble
- kogoto o kurau (小言を食らう): to be scolded, to catch it
- kogu (漕ぐ): to row, to pull the oar
- koguchi (小口): a small sum/amount (of money); a small lot
- kogumaza (小熊座): the Little Bear
- kogunfuntō suru (孤軍奮闘する): to fight unsupported/alone, to cope [with the situation] alone
- kohaba (小幅): a single breadth; narrow limits
- kohaku (琥珀): amber
- kohakuiro no (琥珀色の): amber coloured
- kohan no (湖畔の): lakeside, by/on the lake
- koharubiyori (小春日和): mild autumn weather, an Indian summer
- kohitsuji (子羊): a lamb, lamb
- koi (鯉): a carp
- koi (恋): love
- koi (濃い): dark, deep, thick, strong
- koi o eru (恋を得る): to win her/his heart
- koibito (恋人): a lover, a love, a sweetheart
- koibitodōshi (恋人同士): a pair of lovers
- koibumi (恋文): a love letter
- koigataki (恋敵): a rival in love
- koikina (小粋な): smart, stylish, chic
- koin (コイン): a coin
- koinaka de aru (恋仲である): to be in love
- koinaka ni naru (恋仲になる): to fall in love
- koini (故意に): intentionally, deliberately, on purpose
- koinobori (鯉幟): a carp streamer
- koinrandorī (コイン・ランドリー): a laundromat, a launderette
- koinrokkā (コイン・ロッカー): a (coin-operated) locker
- koinu (小犬): a little dog, a puppy
- koinyōbō (恋女房): one's beloved wife
- koishi (小石): a pebble, gravel
- koishigaru (恋しがる): to long for, to pine for, to yearn after
- koishii (恋しい): dear, beloved, darling
- koishii hito (恋しい人): one's darling
- koisuru (恋する): to love, to fall in love
- koitsu (こいつ): this fellow, this guy, this chap
- koiwazurai (恋煩い): lovesickness
- koiwazurai o suru (恋煩いをする): to be lovesick
- koji (孤児): an orphan
- koji (故事): tradition
- koji ni naru (孤児になる): to be orphaned, to be left an orphan
- koji suru (誇示する): to show proudly, to show off, to display
- koji suru (固辞する): to decline positively
- kojiakeru (こじ開ける): to pry open, to force open, to break open
- kojiin (孤児院): an orphanage
- kojika (子鹿): a fawn
- kojiki (乞食): a beggar; begging
- kojiki o suru (乞食をする): to go begging, to beg one's bread
- kojima (小島): a small island, an islet
- kojin (故人): the deceased, the departed, the dead
- kojin (故人): an individual
- kojin (故人となる): to die
- kojinkeiei (個人経営): private management/enterprise
- kojinkyōju (個人教授): a private lesson
- kojinsa (個人差): an individual variation
- kojinshugi (個人主義): individualism
- kojintekina (個人的な): individual, personal, private
- kojintekini (個人的に): individually, personally, privately
- kojiraireki (故事来歴): the origin and history