Like any great hero, you will need to make sure Kiryu is properly fed so has the strength and energy to defeat others. Because of this, you should make a point to stop in a restaurant every so often. Along with other energy meters, you will also have a Hunger Gauge that will show how full or how hungry Kiryu is. Believe it or not, eating food will actually earn you EXP for each of the five different types it has. You can even discover secret Combinations of food at restaurants that will give you all the more EXP! Of course, feeding Kiryu will also see him restore his health as well.
Since Kiryu's Hunger Gauge will decrease after every little thing you do, including running around the cities and fighting others, you will need to feed him more often than you might think. After just a couple of battles, Kiryu will be ready once again to down loads of goodies. Again, the more food you consume, the more Kiryu's health with return and EXP you will earn. However, if his Hunger Gauge is already full and you continue to consume food, it will begin to have a negative effect on him. Too much of a good thing isn't actually all that good.