Hi, there's a misunderstanding here! The DLC will be free, it will just come out later! If you buy the game when it's released, you'll have only the first three routes, then we'll add the last two routes. Since we wanted our public not to wait too long before playing, that's how we decided to go, so you'll have something to play while we finish the other routes!
You can also wait for all the routes to be released to buy the game, it's up to you!