| 必要 | ひつよう | necessary; needed; essential; indispensable | n4 |
| 必ず | かならず | always; without exception; necessarily; certainly | n4 |
| 必ずしも | かならずしも | (not) always; (not) necessarily; (not) entirely; (not) all | n3 |
| 必須 | ひっす | indispensable; essential; requisite; required | n1 |
| 必死 | ひっし | frantic; frenetic; desperate; inevitable death | n2 |
| 必然 | ひつぜん | inevitable; necessary; certain; sure | n2 |
| 必 | ひつ | definiteness; certainty | |
| 必見 | ひっけん | must-see; not-to-be-missed | |
| 必要性 | ひつようせい | necessity; need | |
| 必ずや | かならずや | certainly; surely; definitely | |
| 必定 | ひつじょう | inevitably; certainly | |
| 必至 | ひっし | inevitable; unavoidable; certain; brinkmate (inevitable checkmate) | n1 |
| 必殺 | ひっさつ | bringing certain death; deadly; knockout (blow) | |
| 必勝 | ひっしょう | certain victory | |
| 必需 | ひつじゅ | necessary | |
| 必然的 | ひつぜんてき | inevitable; necessary | n1 |
| 必読 | ひつどく | must-read; required reading | |
| 必要ない | ひつようない | unnecessary; not needed; not necessary | |
| 必要不可欠 | ひつようふかけつ | absolutely essential; indispensable; vital; critical | |
| 必要書類 | ひつようしょるい | necessary documents; required documents | |
| 必携 | ひっけい | indispensable; essential; must-have; handbook | |
| 不必要 | ふひつよう | unnecessary; needless | n2 |
| 必需品 | ひつじゅひん | necessities; necessary article; requisite; essentials | n1 |
| 必殺技 | ひっさつわざ | killer technique; surefire assassination method; special or lethal move, usu. one unique to a certain fighter or fighting style | |
| 必勝法 | ひっしょうほう | surefire way to win | |
| 必修 | ひっしゅう | required (subject) | |
| 必須条件 | ひっすじょうけん | essential condition | |
| 必用 | ひつよう | necessary; needed; essential; indispensable | n4 |
| 必要最低限 | ひつようさいていげん | bare minimum; minimum necessary (amount, number, etc.) | |
| 必要十分 | ひつようじゅうぶん | necessary and sufficient | |
| 必要事項 | ひつようじこう | necessary items; required items; necessary information; required fields (on a form) | |
| 生活必需品 | せいかつひつじゅひん | daily (living) necessities; necessities; essentials for life | |
| 必中 | ひっちゅう | hitting the target | |
| 必要最小限 | ひつようさいしょうげん | minimum necessary; bare minimum; minimal requirement | |
| 必然性 | ひつぜんせい | necessity; inevitability | n1 |
| 必聴 | ひっちょう | must-listen | |
| 必着 | ひっちゃく | must arrive (no later than; e.g. of an application); must be received; must be delivered; must wear (e.g. a seatbelt) | n1 |
| 生者必滅 | しょうじゃひつめつ | all living things must die | |
| 必要条件 | ひつようじょうけん | necessary condition; requirement | |
| 必修科目 | ひっしゅうかもく | compulsory subject; required subject | |
| 必食 | ひっしょく | must-eat | |
| 信賞必罰 | しんしょうひつばつ | rewards and punishments; rewarding good conduct and punishing evildoing | |
| 必須脂肪酸 | ひっすしぼうさん | essential fatty acid | |
| 必要経費 | ひつようけいひ | necessary expenses; due charges; tax deductible expenses | |
| 必衰 | ひっすい | inevitable decline (decay, collapse, etc.) | |
| 必要悪 | ひつようあく | necessary evil | |
| 絶対必要 | ぜったいひつよう | absolutely necessary | |
| 必携品 | ひっけいひん | must-have; indispensable item; necessities | |
| 必要品 | ひつようひん | necessities | |
| 未必の故意 | みひつのこい | conscious neglect; willful negligence; wilful negligence | |
| 必敗 | ひっぱい | certain defeat | |
| 必置 | ひっち | mandatory requirements (e.g. qualifications, administrative structures, etc.) | |
| 必達 | ひったつ | certain fulfilment; reaching a goal without fail | |
| 必読書 | ひつどくしょ | must-read (book); required reading | |
| 一発必中 | いっぱつひっちゅう | success on the first try (attempt) | |
| 必要労働 | ひつようろうどう | (socially) necessary labour; necessary work | |
| 必須科目 | ひっすかもく | required subject; compulsory course | |
| 必備 | ひつび | indispensable; essential; necessary; must-have | |
| 必捷 | ひっしょう | certain victory | |
| 必治 | ひっち | certain cure | |
| 必滅 | ひつめつ | mortality | |
| 必竟 | ひっきょう | after all; in the end; in short; atyanta (absoluteness) | |
| 必罰 | ひつばつ | inevitability of punishment | |
| 必する | ひっする | to be inevitable; to be certain; to resolve (to do) | |
| 必治薬 | ひっちやく | necessity guaranteed to cure | |
| 必要事 | ひつようじ | necessities | |
| 必要物 | ひつようぶつ | necessities | |
| 必要語 | ひつようご | key word | |
| 必須格 | ひっすかく | indispensable case | |
| 甲必丹 | カピタン | chief trader (of the Dutch trading post at Dejima); captain (of a European ship; Edo period) | |
| 先手必勝 | せんてひっしょう | victory goes to the one who makes the first move; being quick to take action leads to victory; the early bird gets the worm | |
| 後手必敗 | ごてひっぱい | Defeat is inevitable for one who goes second; Being slow to take action inevitably leads to defeat | |
| 必す属性 | ひっすぞくせい | mandatory attribute; required attribute | |
| 必勝不敗 | ひっしょうふはい | certain victory; sure victory; invincibility | |
| 必置規制 | ひっちきせい | government rules on structure, staffing, etc. of local bodies (e.g. police force) | |
| 必要なし | ひつようなし | not required | |
| 必要次第 | ひつようしだい | as necessary (needed); if necessary (needed) | |
| 必要無い | ひつようない | unnecessary; not needed; not necessary | |
| 必須入力 | ひっすにゅうりょく | required entry (e.g. in online forms) | |
| 必須属性 | ひっすぞくせい | mandatory attribute; required attribute | |
| 盛者必衰 | じょうしゃひっすい | even the prosperous inevitably decay; sic transit gloria mundi; all that's fair must fade | |
| 驕兵必敗 | きょうへいひっぱい | defeat is inevitable for an overconfident army; being arrogant and overconfident inevitably leads to defeat; pride comes before a fall | |
| 半数必中界 | はんすうひっちゅうかい | circular error probability (measure of missile accuracy); circular error probable; CEP | |
| 必要とする | ひつようとする | to need; to call for; to require | |
| 必要ならば | ひつようならば | if necessary | |
| 必要メモリ | ひつようメモリ | required memory size | |
| 必死になって | ひっしになって | desperately; for one's dear life | |
| 必要と認める | ひつようとみとめる | to judge as necessary | |
| 必要に応じて | ひつようにおうじて | as necessary; if necessary; as the need arises; as occasion demands | |
| 必要労働時間 | ひつようろうどうじかん | necessary labour time (in Marxian economics) | |
| 必要動作環境 | ひつようどうさかんきょう | (minimum) system requirements | |
| 必要十分条件 | ひつようじゅうぶんじょうけん | necessary and sufficient condition | |
| 必須アミノ酸 | ひっすアミノさん | essential amino acid | |
| 必要は発明の母 | ひつようははつめいのはは | necessity is the mother of invention | |
| 文脈上の必す字句 | ぶんみゃくじょうのひっすじく | contextually required token | |
| 文脈上の必す要素 | ぶんみゃくじょうのひっすようそ | contextually required element | |
| 社会的必要労働時間 | しゃかいてきひつようろうどうじかん | socially necessary labour time | |
| 生ある者は必ず死あり | せいあるものはかならずしあり | no mortal escapes death; all men must die; he who has life, certainly has death | |
| 生有る者は必ず死有り | せいあるものはかならずしあり | no mortal escapes death; all men must die; he who has life, certainly has death | |
| 徳は孤ならず必ず隣あり | とくはこならずかならずとなりあり | the virtuous man will not long remain lonely | |
| 三人行けば必ず我が師有り | さんにんゆけばかならずわがしあり | something can be learned from anyone; if three walk together, I'll have a teacher | |
| 積善の家には必ず余慶あり | せきぜんのいえにはかならずよけいあり | a virtuous family enjoys long prosperity; one's good deeds shall be repaid even to one's descendants | |
| 積善の家には必ず余慶有り | せきぜんのいえにはかならずよけいあり | a virtuous family enjoys long prosperity; one's good deeds shall be repaid even to one's descendants | |
| 3人行けば必ず我が師あり | さんにんゆけばかならずわがしあり | something can be learned from anyone; if three walk together, I'll have a teacher | |
| 積不善の家には必ず余殃あり | せきふぜんのいえにはかならずよおうあり | iniquities of fathers are visited upon their sons | |
| 積不善の家には必ず余殃有り | せきふぜんのいえにはかならずよおうあり | iniquities of fathers are visited upon their sons | |