China is demanding that Japan immediately free the captain of a fishing boat, whose crew was released and flown home earlier today following a tense diplomatic standoff between Beijing and Tokyo. But Japanese police continue to hold the boat's captain, Zhan Qixiong, while investigators decide if he should be charged with deliberately striking a patrol ship and obstructing public officers. Under Japanese law, he can be held for 20 days without charge. His fishing boat collided last Tuesday with two Japanese coast guard ships near a group of tiny uninhabited islands in the East China Sea that both China and Japan claim. China has summoned Japan's ambassador to China four times to protest the fishing boat detentions.