Extra modes
After beating the East's section of the game go to the main menu and you will be able to see all the routes that you took. In your next game, you will also be able to play as the West. After you beat the game with the west, you will unlock battle mode at the main menu. Battle mode allows you to play any battle you want with West or East.

Menu Option
At the option menu, select password and type: YAMOSHITO.