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

He found the hidden place in the room.

He hid the truth from me.

He lied to conceal the truth.

It was revealed that he had a hidden weapon.

He installed a hidden camera in the room.

He started to act immediately.

I couldn't understand his actions.

He remembered the proverb 'A capable hawk hides its talons' and modestly showed his talent.

My butt hurts because I've been sitting for a long time.