expression
gotcha; got you
Casual, colloquial expression used when catching someone or understanding something, similar to English 'gotcha'. Often used playfully or in informal conversation.
「ガッチャ!」と言って、友達の肩をポンと叩いた。
He said 'Gotcha!' and tapped his friend on the shoulder.
説明を聞いて、「あ、ガッチャ」と納得した。
After hearing the explanation, he said 'Ah, gotcha' in understanding.