He is acting in a way that is like 'hide the head but forget the tail'.

He installed a hidden camera in the room.

It was revealed that he had a hidden weapon.

He lied to conceal the truth.

He has a habit of reciting the Nenbutsu every day.

He sent a reminder about tomorrow's meeting by email.

I reminded him about the meeting tomorrow.

Just in case, let's bring an umbrella.

He stuck to his first thought or decision.

He was troubled by various thoughts.