Translation guide
The developmental phase around age two when toddlers become defiant and throw tantrums. In Japanese, this is expressed with set phrases and descriptive language rather than a single word.
Referring to the developmental stage itself
Literally 'devilish two-year-old'. The most direct and common equivalent, used in parenting contexts.
うちの子は今、魔の二歳児で大変です。
My child is in the terrible twos right now, and it's tough.
Talking about a child who is going through the terrible twos
Can also refer to the child themselves. Often used with possessive or descriptive phrases.
あの子は完全に魔の二歳児だね。
That kid is totally in the terrible twos.
Both are very common. 魔の二歳児 emphasizes the difficulty for parents (the 'devilish' aspect), while イヤイヤ期 focuses on the child's behavior of saying 'no' to everything. 第一次反抗期 is more formal and used in written or professional contexts.
While 'terrible twos' implies age two, the Japanese terms can sometimes extend to age three. You might also hear 魔の三歳児 (まのさんさいじ) for 'terrible threes'.
Literally 'no-no period'. A very common, slightly more casual term focusing on the child's refusal behavior.
イヤイヤ期の子どもとどう接すればいいですか？
How should I deal with a child in the terrible twos?
Literally 'first rebellious period'. A more clinical/psychological term, often used in child development contexts.
第一次反抗期は自我の芽生えの表れです。
The terrible twos are a sign of emerging self-awareness.
A child in the 'no-no period'. Very common in everyday conversation.
イヤイヤ期の子を連れての買い物は疲れる。
Shopping with a toddler in the terrible twos is exhausting.