Rai holds a great obsession with Ramen noodles, which is a running gag of the series, for Ramen is generally viewed as a 'cheaper' or lower class, quick-on-the-go food. Rai, the Noblesse who focuses on elegance and class, always wishes to eat ramen, surprising many others.
At the time of his introduction with ramen, Rai thinks it's intended for killing him (seeing chopsticks and garlic) when Shinwoo treats him to ramen because he had no lunch money. Later his fondness of ramen reaches such extremity that Frankenstein begins conducting taste experiments to produce the perfect gourmet ramen for his master. Rai even sent the Lord a ramen packet as present before departing from Lukedonia.