Japan Protests China's Gas Drilling in East China Sea

Japan is upset because China has sent a big ship to drill for gas in the East China Sea.

Japan says this area is disputed and both countries have different ideas about where their borders should be.

They had an agreement to work together on this in 2008, but it fell apart in 2010.

Now, things are even more tense because of some recent political arguments.

Japan thinks China is being unfair by doing this alone, and China thinks the border should be different.

It's like two kids arguing over who gets to play with a toy in a shared backyard.