ナイーブnaiibu

1. na-adjective, nouninnocent; sensitive; uncomplicated; unpretentious; straightforward
   昨日きのうのけんかを気きにしてるの？意外いがいにナイーブなのね。↗

   Are you still letting last night's fight bother you? You're surprisingly sensitive.

• Synonym無邪気むじゃきNeutralChildlike innocence with no ill intent; positive. 「ナイーブ」 also covers sensitivity to hurt or being unschooled in the world.
• Synonym純真じゅんしんNeutralA pure, untainted heart, as in 「純真な心」; positive, but lacks the sensitive-easily-hurt nuance.
• Synonym純情じゅんじょうNeutralPure-hearted, mostly in romantic contexts, as in 「純情な少年」; positive, without the easily-hurt nuance.
• Synonym初々しいういういしいNeutralFresh and green like a newcomer, unsophisticated, as in 「初々しい新入社員」; carries a favorable feel.
• Synonym純朴じゅんぼくNeutralUnpretentious, sincere and honest, as in 「純朴な村人」; positive, approving.
• Synonym純じゅんNeutralPure, innocent character; rarely alone, mostly in compounds like 「純愛」. Also means unmixed, unalloyed.
• SynonymイノセントNeutralLoanword stressing being guiltless or blameless; can also mean innocent. 「ナイーブ」 has no 'not guilty' sense.
• Synonym天真爛漫てんしんらんまんNeutralFour-character idiom for open, artless innocence with a charming feel; mostly describes children or cheerful people.
• Related初心しょしんNeutralRead 「うぶ」, usually written in kana; green about the world, especially in love, as in 「うぶな青年」. 「ナイーブ」 adds the sensitive nuance.
• Related未熟みじゅくNeutralImmature or lacking experience or skill, often critical, as in 「未熟者」; also used for unripe fruit.
• Related無心むしんNeutralFree of distracting thoughts, absorbed and innocent, as in 「無心に遊ぶ」; about single-minded absorption, not sensitivity.
• Related単純たんじゅんNeutralSimple; for people it suggests simple-minded or straightforward, critical or neutral. 「ナイーブ」 leans pure and sensitive.
• Related青いあおいCasualLiterally blue or green; figuratively young and immature, as in 「考えが青い」. Dismissive, mostly colloquial.
• Related世間知らずせけんしらずNeutralIgnorant of how the world works, often critical, as in 「世間知らずのお嬢様」; close to 「ナイーブ」's worldly-inexperience sense.
• RelatedたわいないNeutralChildish or trivial, as in 「たわいない話」; stresses silliness and slightness, unrelated to a sensitive nature.
• Related純潔じゅんけつNeutralPurity or chastity, moral or sexual; not used for a simple, sensitive personality.
• Related天衣無縫てんいむほうWrittenFour-character idiom for artless, unaffected naturalness; also flawless, natural poetry or prose. More written/formal than 「ナイーブ」.
• Related天真てんしんWrittenNatural and unadorned; rarely used alone, mostly in 「天真爛漫」. Leans written/formal.
• RelatedすれてないCasualColloquial: not yet jaded by the world, simple and honest, with a favorable feel, as in 「すれてない子」.
• Related初いうぶいNeutralAdjective form of 「うぶ」: innocent, green, unsophisticated. Rare; people usually say 「うぶな」.
• Related生熟れなまなれWrittenLittle experience or unskilled; rare, and also means unfermented narezushi. In daily speech say 「未熟」.
• Antonym狡猾こうかつNeutralSly and cunning, as in 「狡猾な手口」; the opposite of the innocent, simple 「ナイーブ」.
• AntonymひねくれたNeutralTwisted, perverse temperament; the opposite of the pure, straightforward 「ナイーブ」. Mostly describes personality.

「ナイーブ」 covers both innocent, worldly-inexperienced naivety and a sensitive, easily-hurt nature. For plain childlike innocence pick 「無邪気」 or 「純真」; for critical immaturity or inexperience pick 「未熟」 or 「世間知らず」. Use 「うぶ」 for greenness especially in love, 「純情」 for pure-heartedness in romance, 「初々しい」 for fresh newcomers, 「純朴」 for honest simplicity, 「単純」 for simple-mindedness, and 「青い」 for immature thinking (colloquial, dismissive). Antonyms: 「狡猾」, 「ひねくれた」.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

1. 純真じゅんしんな。無邪気むじゃきな。世間せけん知しらずな。無む思慮しりょな。
2. 素朴そぼくな。単純たんじゅんな。