Sticking a cross into a rice paddy to get its measurements is your specialty. Most people get really confused when they have to measure their rice paddies, but that's where you come in. You plant a cross right in the middle, look down it from one end to the other, and voila! You know the measurements immediately. That's why it's your specialty!
Hearing of your amazing specialty and cross measurement abilities, a centaur (せん) from a far off land recruits you for a job. The centaur’s father has just passed away and the centaur wants you to measure the rice paddies that have been left to him.