He says 'of course' like it's SO OBVIOUS. XD Here's a little insight about what he's talking about:

True Runes are really important to the Suikoden Universe, and in particular, important to Yuber's character. However, rather than infodump at you, I'll let you read this bit of background on your own if you'd like. http://www.suikosource.com/history/truerunes/

The short version is that it's basically what makes him tick-- from his affinity for the chaotic, to his teleportation ability and near-immortality.