打ち明ける
うちあける · uchiakeru · JLPT N1 · verb-ichidan
to confess
打 (strike, open) + ち明ける (clear up, make plain): to strike open the truth and make it clear
打ち = hit or strike, 明ける = to dawn or make clear. Together: strike something open so the hidden truth comes out. Confessing is opening your heart and letting the secret out.
打 — hand radical 扌 + nail 丁
打 combines the hand radical 扌 (action with the hand) with 丁 (originally a nail), suggesting striking or hitting with the hand. 丁 also serves as a phonetic hint in older readings. The meaning broadened from 'to strike' to a general verb for many hand-based actions, like 打电话 'make a phone call'.