Translation guide
The phrase 'at heart' describes someone's true, fundamental nature or deepest feelings, often in contrast to their outward appearance or behavior. It can also mean 'in essence' or 'basically' when describing the core character of a person or thing.
To express that someone is fundamentally a certain kind of person, despite appearances or actions.
Literally 'the root is', this is a very common and natural way to say someone is essentially a certain type of person. Often used with adjectives or nouns describing character.
彼は根は優しい人だ。
He is a kind person at heart.
根は真面目なんだけど、いつもふざけている。
He's serious at heart, but he's always joking around.
To describe the fundamental nature of something, not just a person. Similar to 'essentially' or 'basically'.
Means 'basically' or 'fundamentally'. Used for both people and things to describe their core nature.
この計画は基本的には良いアイデアだ。
This plan is a good idea at heart.
Do not translate 'at heart' literally as 心に (こころに) or 心で (こころで). These mean 'in the heart' as a location, not the idiomatic sense of true nature. Use the phrases above instead.
Means 'in one's heart/mind', emphasizing inner feelings or thoughts that may not be shown outwardly.
心の中では彼女のことを尊敬している。
At heart, I respect her.
Means 'actually' or 'in truth', often used to reveal someone's real nature or feelings.
本当は彼は寂しがり屋だ。
He is actually a lonely person at heart.
Means 'originally' or 'by nature', used to describe inherent character. Slightly more formal or written.
彼は本来は心優しい人間だ。
He is a kind-hearted person at heart.
He is an honest person at heart.
Means 'essentially' or 'in essence'. More formal and often used in analytical contexts.
この問題は本質的にはコミュニケーション不足だ。
At heart, this problem is a lack of communication.