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secret intention; ulterior motive
kanji "heart" radical at bottom
彼には何か下心があるように見える。
He seems to have some kind of ulterior motive.
下心なしで純粋に手伝ってあげたのに。
I purely helped without any ulterior motives though.
彼女の親切には下心があったのか。
Did her kindness have an ulterior motive?